MAINT improve isolation for micropip tests. I added a new `wheel_base` fixture which creates a new temporary directory and mocks `site.getsitepackages()` to return it. I also removed the `WHEEL_BASE` global variable from micropip and instead calculate it each time in `micropip.install`.
# This file gets copied into the Modules/ folder when building
# newlib configurations which do not support dynamic library
# loading.
#
# See build/Python-*/Modules/Setup for more details

*static*

array arraymodule.c	# array objects
audioop audioop.c	# Operations on audio samples
math mathmodule.c _math.c # -lm # math library functions, e.g. sin()
cmath cmathmodule.c # complex math functions
_contextvars _contextvarsmodule.c
_struct _struct.c	# binary structure packing/unpacking
_random _randommodule.c	# Random number generator
_bisect _bisectmodule.c	# Bisection algorithms
_datetime _datetimemodule.c
_heapq _heapqmodule.c
_json _json.c
_csv _csv.c

CTYPES_FLAGS=-DHAVE_FFI_PREP_CIF_VAR=1 -DHAVE_FFI_PREP_CLOSURE_LOC=1 -DHAVE_FFI_CLOSURE_ALLOC=1
_ctypes _ctypes/_ctypes.c _ctypes/callbacks.c _ctypes/callproc.c _ctypes/cfield.c _ctypes/stgdict.c $(CTYPES_FLAGS)

unicodedata unicodedata.c
_pickle _pickle.c

_socket socketmodule.c
select selectmodule.c
_posixsubprocess _posixsubprocess.c
binascii binascii.c

zlib zlibmodule.c

pyexpat expat/xmlparse.c expat/xmlrole.c expat/xmltok.c pyexpat.c -I$(srcdir)/Modules/expat -DHAVE_EXPAT_CONFIG_H -DUSE_PYEXPAT_CAPI -DXML_POOR_ENTROPY

_sha1 sha1module.c
_sha256 sha256module.c
_sha512 sha512module.c
_sha3 _sha3/sha3module.c
_md5 md5module.c
_blake2 _blake2/blake2module.c _blake2/blake2b_impl.c _blake2/blake2s_impl.c

# If we put this directly in the next line, makesetup incorrectly views the
# line as a definition line, instead of specifying a module. We bypass this
# problem by defining an extra variable that contains the =, and this line is
# correctly viewed as a definition line. We need extra quotes to make gcc think
# we want to define MODULE_NAME to be the string "sqlite" instead of the
# abstract symbol sqlite.
SQLITEMODULENAME=MODULE_NAME=\'"sqlite"\'
_sqlite3 _sqlite/cache.c _sqlite/connection.c _sqlite/cursor.c _sqlite/microprotocols.c _sqlite/module.c _sqlite/prepare_protocol.c _sqlite/row.c _sqlite/statement.c _sqlite/util.c -D$(SQLITEMODULENAME) -lsqlite3
_crypt _cryptmodule.c
_bz2 _bz2module.c -lbz2

_queue _queuemodule.c

#future_builtins future_builtins.c

_multibytecodec cjkcodecs/multibytecodec.c

_codecs_cn cjkcodecs/_codecs_cn.c
_codecs_hk cjkcodecs/_codecs_hk.c
_codecs_iso2022 cjkcodecs/_codecs_iso2022.c
_codecs_jp cjkcodecs/_codecs_jp.c
_codecs_kr cjkcodecs/_codecs_kr.c
_codecs_tw cjkcodecs/_codecs_tw.c

_lsprof _lsprof.c rotatingtree.c

_decimal _decimal/_decimal.c _decimal/libmpdec/basearith.c _decimal/libmpdec/constants.c _decimal/libmpdec/context.c _decimal/libmpdec/convolute.c _decimal/libmpdec/crt.c _decimal/libmpdec/difradix2.c _decimal/libmpdec/fnt.c _decimal/libmpdec/fourstep.c _decimal/libmpdec/io.c _decimal/libmpdec/mpalloc.c _decimal/libmpdec/mpdecimal.c _decimal/libmpdec/numbertheory.c _decimal/libmpdec/sixstep.c _decimal/libmpdec/transpose.c -I$(srcdir)/Modules/_decimal/libmpdec
mmap mmapmodule.c
_xxsubinterpreters _xxsubinterpretersmodule.c

# This file gets copied into the Modules/ folder when building
# newlib configurations which do not support dynamic library
# loading.
#
# See build/Python-*/Modules/Setup for more details

*static*

array arraymodule.c	# array objects
audioop audioop.c	# Operations on audio samples
math mathmodule.c _math.c # -lm # math library functions, e.g. sin()
cmath cmathmodule.c # complex math functions
_contextvars _contextvarsmodule.c
_struct _struct.c	# binary structure packing/unpacking
_random _randommodule.c	# Random number generator
_bisect _bisectmodule.c	# Bisection algorithms
_datetime _datetimemodule.c
_heapq _heapqmodule.c
_json _json.c
_csv _csv.c

CTYPES_FLAGS=-DHAVE_FFI_PREP_CIF_VAR=1 -DHAVE_FFI_PREP_CLOSURE_LOC=1 -DHAVE_FFI_CLOSURE_ALLOC=1
_ctypes _ctypes/_ctypes.c _ctypes/callbacks.c _ctypes/callproc.c _ctypes/cfield.c _ctypes/stgdict.c $(CTYPES_FLAGS)

unicodedata unicodedata.c
_pickle _pickle.c

_socket socketmodule.c
select selectmodule.c
_posixsubprocess _posixsubprocess.c
binascii binascii.c

zlib zlibmodule.c

pyexpat expat/xmlparse.c expat/xmlrole.c expat/xmltok.c pyexpat.c -I$(srcdir)/Modules/expat -DHAVE_EXPAT_CONFIG_H -DUSE_PYEXPAT_CAPI -DXML_POOR_ENTROPY

_sha1 sha1module.c
_sha256 sha256module.c
_sha512 sha512module.c
_sha3 _sha3/sha3module.c
_md5 md5module.c
_blake2 _blake2/blake2module.c _blake2/blake2b_impl.c _blake2/blake2s_impl.c

# If we put this directly in the next line, makesetup incorrectly views the
# line as a definition line, instead of specifying a module. We bypass this
# problem by defining an extra variable that contains the =, and this line is
# correctly viewed as a definition line. We need extra quotes to make gcc think
# we want to define MODULE_NAME to be the string "sqlite" instead of the
# abstract symbol sqlite.
SQLITEMODULENAME=MODULE_NAME=\'"sqlite"\'
_sqlite3 _sqlite/cache.c _sqlite/connection.c _sqlite/cursor.c _sqlite/microprotocols.c _sqlite/module.c _sqlite/prepare_protocol.c _sqlite/row.c _sqlite/statement.c _sqlite/util.c -D$(SQLITEMODULENAME) -lsqlite3
_crypt _cryptmodule.c
_bz2 _bz2module.c -lbz2

_queue _queuemodule.c

#future_builtins future_builtins.c

_multibytecodec cjkcodecs/multibytecodec.c

_codecs_cn cjkcodecs/_codecs_cn.c
_codecs_hk cjkcodecs/_codecs_hk.c
_codecs_iso2022 cjkcodecs/_codecs_iso2022.c
_codecs_jp cjkcodecs/_codecs_jp.c
_codecs_kr cjkcodecs/_codecs_kr.c
_codecs_tw cjkcodecs/_codecs_tw.c

_lsprof _lsprof.c rotatingtree.c

_decimal _decimal/_decimal.c _decimal/libmpdec/basearith.c _decimal/libmpdec/constants.c _decimal/libmpdec/context.c _decimal/libmpdec/convolute.c _decimal/libmpdec/crt.c _decimal/libmpdec/difradix2.c _decimal/libmpdec/fnt.c _decimal/libmpdec/fourstep.c _decimal/libmpdec/io.c _decimal/libmpdec/mpalloc.c _decimal/libmpdec/mpdecimal.c _decimal/libmpdec/numbertheory.c _decimal/libmpdec/sixstep.c _decimal/libmpdec/transpose.c -I$(srcdir)/Modules/_decimal/libmpdec
mmap mmapmodule.c
_xxsubinterpreters _xxsubinterpretersmodule.c
