fix(google-crc32c): add explicit license declaration to pyproject.toml

[anishesg]

The google-crc32c package was missing a license field in the [project] section of pyproject.toml after being migrated from setup.py. Without this field, PyPI cannot display license metadata for the package, which breaks compliance checking workflows that validate open-source licenses during installation.

The fix adds license = { text = "Apache 2.0" } to packages/google-crc32c/pyproject.toml, matching the license declaration format used by other libraries in this repo (e.g., google-api-core). An audit of the other pyproject.toml files in packages/ found that google-crc32c is the only package with a [project] section that was missing this field.

• Open an issue (bug/issue) before writing code to discuss the change, evaluate designs, and agree on the general idea
• Ensure tests and linter pass
• Code coverage does not decrease (if source code was changed)
• Appropriate docs were updated (if necessary)

Fixes #16603

[gemini-code-assist]

Code Review

This pull request updates the pyproject.toml file for the google-crc32c package to explicitly include the license information as Apache 2.0. I have no feedback to provide as there were no review comments and the change is a standard metadata update.

[anishesg]

Closing — this repo requires internal multi-approver flow and a one-line metadata addition is unlikely to get through. Not worth the overhead.