Bump Ruby to 3.3.12 to fix CVE-2026-41316 (erb)

What does this MR do?

Bumps Ruby from 3.3.11 to 3.3.12 to fix CVE-2026-41316.

Ruby 3.3.12 was released on 2026-07-16 and includes erb 4.0.3.1 which fixes CVE-2026-41316.

Replace REPLACE_WITH_SHA256_FROM_RUBY_RELEASE_PAGE with the actual SHA256 value.

Related changes required

A corresponding MR is needed in gitlab-omnibus-builder to:

1. Update RUBY_VERSION=3.3.12 in docker/VERSIONS
2. Build and tag a new builder image
3. Update BUILDER_IMAGE_REVISION in gitlab-ci-config/variables.yml in this repo to the new builder tag

Related issues

Closes #9982

Checklist

See Definition of done.

Required

• MR title and description are up to date, accurate, and descriptive.
• MR targeting the appropriate branch.
• Latest Merge Result pipeline is green.
• When ready for review, MR is labeled workflowready for review per the Distribution MR workflow.
• The UBT version and corresponding checksum hash have been updated and referenced in the merge request if applicable.
  • UBT EE pipeline (Trigger:ee-package-ubt) is green

For GitLab team members

• The manual Trigger:ee-package jobs have a green pipeline running against latest commit.
• If config/software or config/patches directories are changed, make sure the build-package-on-all-os job within the Trigger:ee-package downstream pipeline succeeded.
• If you are changing anything SSL related, then the Trigger:package:fips manual job within the Trigger:ee-package downstream pipeline must succeed.
• If CI configuration is changed, the branch must be pushed to dev.gitlab.org to confirm regular branch builds aren't broken.

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes.
• Documentation created/updated.
• Tests added.
• Integration tests added to GitLab QA.
• Equivalent MR/issue for the GitLab Chart opened.
• Validate potential values for new configuration settings.