Switch from PurePath#as_uri to PurePath#joinpath for our test that PurePath methods get inherited

[A5rocks]

as_uri is deprecated in PurePath. This commit also introduces a test to ensure users have a workaround that is not deprecated.

Failing test run: https://github.com/python-trio/trio/actions/runs/14393482504/job/40364976912

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00000%. Comparing base (5848b41) to head (b7177b0).
Report is 12 commits behind head on main.

Additional details and impacted files

@@               Coverage Diff                @@
##                 main        #3249    +/-   ##
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  Coverage   100.00000%   100.00000%            
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  Files             122          124     +2     
  Lines           18757        19005   +248     
  Branches         1269         1295    +26     
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+ Hits            18757        19005   +248     

Files with missing lines	Coverage Δ
src/trio/_path.py	100.00000% <100.00000%> (ø)
src/trio/_tests/test_path.py	100.00000% <100.00000%> (ø)

... and 6 files with indirect coverage changes

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[Zac-HD]

IMO we should define a sync trio.Path.as_uri() method; it's not a pure function, but os.fsencode() doesn't do IO that I'd want to make async.

and then I think the test change is just to find a different PurePath method for test_forward_methods_without_rewrap.

[A5rocks]

I wasn't too sure about doing that because there's no fundamental reason that has to be on trio.Path other than historical, and I wasn't sure if there's other sync methods on pathlib.Path that are not on pathlib.PurePath yet still don't do anything bad. (so should we just support all of them? We should have a consistent recommendation that applies for this new as_uri as well.)

And users can do pathlib.Path.as_uri(some_trio_path) to work around the deprecation warning, because trio.Path supports everything as_uri needs.

[Zac-HD]

IMO "maintaining 1:1 compatibility with existing code" is enough reason in this case, and right now unblocking CI feels more urgent than answering those other API design questions 😅

(but for completeness: I'd like trio.Path to support every method on pathlib.Path, async if they do IO and sync if they just depend on OS state as in this case - I think the latter is rare though)

[Zac-HD]

Looks great - thanks for jumping on this @A5rocks!