Add a GitHub Action to lint and test Python code

[cclauss]

The code in this repo is vendored into V8 and contains the only Python Syntax Errors in the V8 codebase that ruff is able to find. So let's put some automated testing in place.

Fixes #8 (This was broken in #4.)
Fixes #10 (This should have been merged when it was proposed.)
Fixes #11 (The solution in #10 was better.)
Similar to #7 (This should have been merged when it was proposed.)

Test results: https://github.com/cclauss/test262-harness-py/actions

1. Lint with https://beta.ruff.rs/docs
2. Test with https://docs.pytest.org

Fix Python Syntax Errors:
Use python-modernize to remove Python 3 syntax errors without breaking compatibility with legacy Python 2.

python-modernize --fix print  --write src/test262.py src/_packager.py
python-modernize --fix except --write src/test262.py

pytest initially failed because of #8 so...

• parseTestRecord.py: Restore stripHeader which was removed without running the tests in Incorporate changes from test262/41edfcebce1a85096 #4
• Fix more pytests by adding the_monkeyYaml.py change from None --> 0 proposed Make monkeyYaml Python3 compatible #10

---

% pytest --ignore=test/test_common.py --ignore=test/test_parseTestRecord.py

============================= test session starts ==============================
platform linux -- Python 3.10.6, pytest-7.3.1, pluggy-1.0.0
rootdir: /home/runner/work/test262-harness-py/test262-harness-py
collected 37 items

test/test_monkeyYaml.py ............................                     [ 75%]
test/test_test262.py .........                                           [100%]

=============================== warnings summary ===============================
[ ... ]
======================= 37 passed, 24 warnings in 0.09s ========================

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My bet would be that the remaining failing tests in test/test_common.py and test/test_parseTestRecord.py could be fixed by completely or partially reverting #4

@erights @jugglinmike @richardlau @gsnedders @mi-ac Your reviews, please.