feat(api_core): add deprecation warning for grpcio < 1.83.0 for PQC

[ohmayr]

Adds deprecation warnings for grpcio < 1.83.0 to google.api_core._python_package_support.
In October 2026, Google Cloud client libraries will raise their minimum requirements to enforce grpcio >= 1.83.0 for Post-Quantum Cryptography (PQC) support.

Towards: b/537446703

[gemini-code-assist]

Code Review

This pull request introduces a dependency check and warning for grpcio < 1.83.0 to support the migration to Post-Quantum Cryptography (PQC). It updates version parsing to handle pre-release versions, fixes an f-string formatting bug in deprecation warnings, and adds corresponding unit tests. Feedback suggests replacing the placeholder XXXXX in the pyproject.toml warning filter with the actual GitHub issue number before merging.

[daniel-sanche]

A couple questions to make sure I'm understanding this right, but mostly looks good so far