ci: Add Python 3.12 image support

[Zgardan-Dumitru]

Add Python 3.12 image support

Summary

Adds Python 3.12 as a supported base image alongside the existing Python 3.10, parameterizing the Python version across all Dockerfiles and CI workflows.

Changes

Dockerfiles — All three Dockerfiles (Dockerfile, Dockerfile.base, Dockerfile.build) now accept a PYTHON_VERSION build arg (defaults to 3.12) instead of hardcoding python:3.10-slim.

CI Workflows:

• build-base-image.yml — Added python-version matrix (3.10, 3.12). Passes PYTHON_VERSION build-arg and tags images as quara/blez-base:<python-version>.
• build-cp-image.yml — Added python-version matrix (3.10, 3.12). Passes PYTHON_VERSION build-arg and tags images as quara/blez-build:<python-version>.
• build-blez-image.yml — Split single version matrix into python-version × bluez-version matrix. Tags images as quara/blez:<python-version>_<bluez-version>. Passes both PYTHON_VERSION and BLUEZ_VERSION build-args.
• build-bluez.yml — Added 3.12_5.66 and 3.12_5.85 to the version matrix. Now parses both PYTHON_VERSION and BLUEZ_VERSION from the composite matrix value and passes both to cp-build.sh.

Scripts:

• cp-build.sh — Updated calling convention from $PLATFORM $BLUEZ_VERSION... to $PLATFORM $PYTHON_VERSION $BLUEZ_VERSION.... Uses quara/blez-build:<python-version> instead of the non-existent :latest tag.

Docs — Updated README.md with Docker build examples for both Python versions.

Breaking Changes

• cp-build.sh now requires a Python version as the second argument:

  # Before
  ./scripts/cp-build.sh linux/amd64 5.66
  # After
  ./scripts/cp-build.sh linux/amd64 3.12 5.66

Image Matrix

Image	Tags
quara/blez-base	3.10, 3.12
quara/blez-build	3.10, 3.12
quara/blez	3.10_5.66, 3.10_5.85, 3.12_5.66, 3.12_5.85