Log Message:
py-fakefs: updated to 4.5.6

Version 4.5.6

Changes
* minimum supported pytest version is now 3.0 (older versions do not work
  properly with current Python versions)

Fixes
* only skip `_pytest.pathlib` in pytest versions where it is actually present

Infrastructure
* add tests with different pytest versions, starting with 3.0

Version 4.5.5

Fixes
* correctly handle file system space for files opened in write mode
* correctly handle reading/writing pipes via file
* disallow `encoding` argument on binary `open()`
* fixed compatibility issue with pytest 7.0.0