Use PEP 562 instead of _ModuleWithDeprecations

[A5rocks]

Presumably fixes #2135 but I haven't checked this and I'm not sure how to test this (as it relies on cloudpickle not pickle).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 56.17373%. Comparing base (b6813ed) to head (6f94687).
Report is 11 commits behind head on main.

❌ Your project status has failed because the head coverage (56.17373%) is below the target coverage (100.00000%). You can increase the head coverage or adjust the target coverage.

❗ There is a different number of reports uploaded between BASE (b6813ed) and HEAD (6f94687). Click for more details.

HEAD has 70 uploads less than BASE

Flag	BASE (b6813ed)	HEAD (6f94687)
macOS	21	14
3.11	14	9
3.10	12	8
Ubuntu	24	16
3.12	15	10
3.14	12	8
3.9	25	16
Cython	8	4
Alpine	3	2
3.13	14	9
Windows	45	30
pypy-3.10	9	6

Additional details and impacted files

@@                  Coverage Diff                  @@
##                 main       #3230          +/-   ##
=====================================================
- Coverage   100.00000%   56.17373%   -43.82627%     
=====================================================
  Files             124         246         +122     
  Lines           18779       37530       +18751     
  Branches         1269        2538        +1269     
=====================================================
+ Hits            18779       21082        +2303     
- Misses              0       16320       +16320     
- Partials            0         128         +128     

Files with missing lines	Coverage Δ
src/trio/__init__.py	100.00000% <100.00000%> (ø)
src/trio/_deprecate.py	100.00000% <100.00000%> (ø)
src/trio/_tests/module_with_deprecations.py	100.00000% <100.00000%> (ø)
src/trio/_tests/test_deprecate.py	100.00000% <100.00000%> (ø)

... and 126 files with indirect coverage changes

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