…on (#537)

* Adapt Dockerfiles and workflows to redis modules modernization
* Support pulling Redis sources from a fork

Allows to merge .github/ contents from unstable to other branches
without conflicts

Handle both modules build variants: modern and old

Install yq only when build is custom

Internal-release tarballs may not bundle redis-full module sources, but
the modules-update fallback was gated entirely behind custom_build, so
internal releases (built with custom_build=false) never cloned them.

Add an `internal` template flag: keep yq version-pinning custom-only, but
run the .prepared-gated modules-update for custom OR internal builds.
Internal releases re-render with `-s internal true` at build time, so the
committed official Dockerfile (custom_build=false, internal=false) stays
clean and byte-identical to HEAD.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Fixes version comparison

Update redis_version package

Remove unsupported architectures for bookworm