Add Python SAST (CodeQL + Bandit) to CI

Introduce static application security testing (SAST) coverage for the MariaDB Connector/Python, mirroring the analysis tooling already in place for the Java, C, and Node.js connectors (see CONJS-357).

Two complementary tools will be added:

• CodeQL: deep taint and dataflow analysis, the Python/C equivalent of Infer used in the other connectors. Because this repository ships both pure-Python code (mariadb, mariadb_shared) and a C extension (mariadb-c), CodeQL will be configured for both the python and cpp language packs so the native code is covered as well.
• Bandit: lightweight syntactic security checks (the Python counterpart to eslint-plugin-security), integrated into the existing lint tooling (.pre-commit-config.yaml / flake8 config) so findings surface locally as well as in CI.