Run tests for 3.11

[d5h]

This mainly adds Python 3.10 and 3.11 for testing. It also has some other minor fixes listed below. It has no functionality changes so I won't push a new release for this.

Changes:

• Runs tests for all major versions on Python from 3.7 to 3.11 in GHA
• Updates mypy since the old version can't build the typed-ast extension with Python 3.11
• Cleans up the test action so it doesn't try to run every nox session, only the ones for the Python version under test (much less noisy)
• Fix a bug where pytest-asyncio wasn't installed by nox so one of the tests was skipped
• Updates coverage because there was a bug in the old version which was making the test output noisy
• Needed to format changes, and needed to update black, which formatted some irrelevant code
• Increase test verbosity

Note: this PR doesn't actually cause test coverage to drop, despite what Codecov is reporting. Codecov's baseline is very old, I believe because they suspended my Codecov account due to inactivity. The coverage baseline it's using was prior to asyncio's addition.

[codecov-commenter]

Codecov Report

Merging #34 (4252b41) into master (30b5173) will decrease coverage by 4.69%.
The diff coverage is 91.23%.

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@@             Coverage Diff             @@
##            master      #34      +/-   ##
===========================================
- Coverage   100.00%   95.31%   -4.69%     
===========================================
  Files            7        7              
  Lines          211      363     +152     
  Branches        15       49      +34     
===========================================
+ Hits           211      346     +135     
- Misses           0       14      +14     
- Partials         0        3       +3     

Impacted Files	Coverage Δ
src/grpc_interceptor/testing/dummy_client.py	91.36% <89.09%> (-8.64%)	⬇️
src/grpc_interceptor/server.py	95.08% <91.42%> (-4.92%)	⬇️
src/grpc_interceptor/exception_to_status.py	96.42% <95.65%> (-3.58%)	⬇️
src/grpc_interceptor/__init__.py	100.00% <100.00%> (ø)
src/grpc_interceptor/client.py	100.00% <100.00%> (ø)

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