fix(crc32c): escape the version dot and anchor the pyenv check regex

[chalmerlowe]

Problem

The OS X python wheel build script (build_python_wheel.sh) checks if a Python version is installed in pyenv before building:

if [ -z"$(pyenv versions --bare | grep $version)" ]

When $version is 3.14, this expands to grep 3.14. Because the dot (.) is not escaped, it is treated as a wildcard and will also match the substring 3.13.14 (which contains 3.14 at the end). This results in a false positive, causing the script to skip compiling Python 3.14. The script then fails when executing pyenv shell 3.14 with a "version not installed" error.

Solution

Escape the version dots in bash: ${version//./\.}.
Anchor the grep match with line start (^) and word boundaries (\b) to ensure it only matches the exact version line (e.g. ^3\.14\b instead of matching 3.13.14).
Applied this fix to both build_python_wheel.sh and publish_python_wheel.sh.

Blocks: #17642

[gemini-code-assist]

Code Review

This pull request improves Python version matching in macOS build and publish scripts by escaping dots and using anchors/word boundaries in grep patterns. The feedback suggests refactoring the bash conditional checks from [ -z "$(pipeline | grep ...)" ] to a more idiomatic and efficient if ! pipeline | grep -q ...; then pattern to avoid unnecessary subshells and string comparisons.

[chalmerlowe]

Re: the failing cover test:

When google-crc32c gets a change to core code, it triggers as a diff in CI/CD and attempts to run unittests in the unit job in workflows/unittest.yml.
Within that job the unit nox session is run via a call to ci/run_conditional_tests.sh.

However... in the crc32c noxfile.py it uses session.skip for unit tests because they are not implemented.

This means NO coverage results are produced.
Which means when the unittest.yml file rolls down to the step that runs coverage, it blows up.

Note

running coverage is entirely managed in the unittest.yml file.
It does NOT run as a nox session defined in the crc32c noxfile.py. In fact there is no cover session, such as we have in other packages.
Thus we can't just go in and tell nox to skip the cover session the way we did with the unit session.

OPTIONS under consideration:

1. Add a filter in the unittest.yml to ignore crc32c when trying launch coverage. We don't yet know how that works in terms of publishing a "success" result so that the CI/CD check succeeds.
2. Add a dummy test (with dummy output) in the crc32c noxfile unit test to create coverage files that reflect 100% coverage for crc32c.

[chalmerlowe]

Re: the failing cover test:

An alternate approach was taken and merged into main that solves the majority of the issues but still had a minor problem with google-crc32c. this PR addresses that last edge case.