Updates after dropping Python 3.6 and 3.7

[hugovk]

Fix some things left over from the drop of EOL Python 3.6 and 3.7:

# TODO: Py3.6 compatibility; os.fsdecode not required in Py3.7

Replace os.fsdecode() with str(), because they can be pathlib Paths.

Also need things like archive.__str__.return_value = "/path/to/download.zip" for the MagicMock objects.

---

    # Consider to remove if block when we drop py3.7 support, only keep statements from else.
    # MagicMock below py3.8 doesn't have __fspath__ attribute.

The if/else blocks (they used to look like 05c50b9) have already been cleaned up (presumably by pyupgrade), so remove these old comments.

PR Checklist:

• All new features have been tested
• [n/a] All new features have been documented
• I have read the CONTRIBUTING.md file
• I will abide by the code of conduct

[freakboy3742]

The cleanups of Py3.6/3.7 detritus are definitely required and appreciated; however, the usage of os.fsdecode is deliberate. This is based on advice from Brett Cannon, (provided in many places; this is one example), my understanding is that os.fsdecode() is preferred for rendering Pathlib objects, in particular because of None handling.

If you've got a different understanding, let us know what I've missed (or misunderstood).

[hugovk]

Ah right, I was mainly going on the comments, so will re-instate the os.fsdecode calls.

And keep the removal of the # TODO: Py3.6 compatibility; os.fsdecode not required in Py3.7 comments?

[freakboy3742]

And keep the removal of the # TODO: Py3.6 compatibility; os.fsdecode not required in Py3.7 comments?

Those comments can all be burned :-) You guessed correctly that they were all left in because pyuprade removed an if/else branch, but didn't pick up the comment explaining the branch.

[hugovk]

Pushed! Let me know if you'd prefer a fixup/rebase.

[freakboy3742]

Awesome - thanks for the 🧹 !