Ruby

[ruby/rubygems] Restore rb_sys dependency for Rust

https://github.com/ruby/rubygems/commit/7cd3b9a08a

Bump the github-actions group across 1 directory with 5 updates

Bumps the github-actions group with 5 updates in the / directory:

Skip cleaning up the default docker image to avoid redundant pulls

The default image (clang-20) is reused across multiple steps within
the same job. Only remove non-default images after use.

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

Remove stephanmisc/docuum dependency to avoid DockerHub rate limits

Replace the docuum service container with a simple docker rmi step
after each compilation. This avoids pulling an external image from
DockerHub, which was causing rate limit issues.

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

Add arm-to-x86 cross-compile matrix and generalize apt setup

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

Add cross-compile workflow for out-of-source ARM build testing

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

Revert generating sources in make-snapshot

Fall back writing prism sources to the current directory

Add rule for dummy config.h

Update rbinc files for snapshots