ci: modernize CU actions

[jkowalleck]

Description

bump CI actions to latest versions, and pin them

Resolves or fixes issue:

AI Tool Disclosure

• My contribution does not include any AI-generated content
• My contribution includes AI-generated content, as disclosed below:
  • AI Tools: [e.g. GitHub CoPilot, ChatGPT, JetBrains Junie etc.]
  • LLMs and versions: [e.g. GPT-4.1, Claude Haiku 4.5, Gemini 2.5 Pro etc.]
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Affirmation

• My code follows the CONTRIBUTING.md guidelines

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

View in Codacy

🟢 Coverage ∅ diff coverage · +0.00% coverage variation

Metric	Results
Coverage variation	✅ +0.00% coverage variation (-1.00%)
Diff coverage	✅ ∅ diff coverage

View coverage diff in Codacy

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (188b9c5)	274	240	87.59%
Head commit (d95ecaa)	274 (+0)	240 (+0)	87.59% (+0.00%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#70)	0	0	∅ (not applicable)

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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[Copilot]

Pull request overview

This PR modernizes the GitHub Actions Ruby CI workflow by making the steps more explicit and pinning action dependencies.

Changes:

• Pin actions/checkout and ruby/setup-ruby to specific commits and add step names/comments for clarity.
• (Intended) improve maintainability of the workflow steps by making them more self-describing.

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[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.