Run core tests in Safari. Partially addresses https://github.com/pyodide/pyodide/issues/989

It runs, but there are several test failures, I'll open separate issues about those.
package:
  name: nltk
  version: "3.7"
  top-level:
    - nltk
source:
  sha256: ba3de02490308b248f9b94c8bc1ac0683e9aa2ec49ee78536d8667afb5e3eec8
  url: https://files.pythonhosted.org/packages/43/0b/8298798bc5a9a007b7cae3f846a3d9a325953e0f9c238affa478b4d59324/nltk-3.7-py3-none-any.whl
requirements:
  run:
    - regex
    - sqlite3
about:
  home: https://www.nltk.org/
  PyPI: https://pypi.org/project/nltk
  summary: Natural Language Toolkit
  license: Apache License, Version 2.0

package:
  name: nltk
  version: "3.7"
  top-level:
    - nltk
source:
  sha256: ba3de02490308b248f9b94c8bc1ac0683e9aa2ec49ee78536d8667afb5e3eec8
  url: https://files.pythonhosted.org/packages/43/0b/8298798bc5a9a007b7cae3f846a3d9a325953e0f9c238affa478b4d59324/nltk-3.7-py3-none-any.whl
requirements:
  run:
    - regex
    - sqlite3
about:
  home: https://www.nltk.org/
  PyPI: https://pypi.org/project/nltk
  summary: Natural Language Toolkit
  license: Apache License, Version 2.0
