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: future
  version: 0.18.2
  top-level:
    - future
source:
  sha256: b1bead90b70cf6ec3f0710ae53a525360fa360d306a86583adc6bf83a4db537d
  url: https://files.pythonhosted.org/packages/45/0b/38b06fd9b92dc2b68d58b75f900e97884c45bedd2ff83203d933cf5851c9/future-0.18.2.tar.gz
about:
  home: https://python-future.org
  PyPI: https://pypi.org/project/future
  summary: Clean single-source support for Python 3 and 2
  license: MIT

package:
  name: future
  version: 0.18.2
  top-level:
    - future
source:
  sha256: b1bead90b70cf6ec3f0710ae53a525360fa360d306a86583adc6bf83a4db537d
  url: https://files.pythonhosted.org/packages/45/0b/38b06fd9b92dc2b68d58b75f900e97884c45bedd2ff83203d933cf5851c9/future-0.18.2.tar.gz
about:
  home: https://python-future.org
  PyPI: https://pypi.org/project/future
  summary: Clean single-source support for Python 3 and 2
  license: MIT
