🌱 Fix PR verifier by replacing deprecated Docker action

[justaugustus]

What kind of change does this PR introduce?

Bug fix - Replaces deprecated Docker action that was causing all PR verifier checks to fail.

• PR title follows the guidelines defined in our pull request documentation

What is the current behavior?

The PR verifier check is failing for all pull requests with error: "Pull gcr.io/kubebuilder/pr-verifier:v0.4.3: failure"

The kubebuilder-release-tools Docker image became unavailable on March 18, 2025, as announced in kubernetes-sigs/kubebuilder-release-tools#60.

What is the new behavior (if this is a feature change)?

• Tests for the changes have been added (for bug fixes/features)

The PR verifier now uses a shell script (scripts/verify-pr-title.sh) instead of the deprecated Docker action. The script:

• Performs PR title verification for required emoji prefixes
• Supports both emoji (🌱) and :emoji: (:seedling:) formats
• Validates input safely (length limits, safe output handling)
• Matches the exact emoji list from CONTRIBUTING.md

Supported emoji prefixes:

• ⚠ Breaking change (:warning:)
• ✨ Non-breaking feature (:sparkles:)
• 🐛 Patch fix (:bug:)
• 📖 Documentation changes (user or developer) (:book:)
• 🌱 Infra/Tests/Other (:seedling:)
• 👻 No release note (:ghost:)

Tested locally with:

• ✅ All supported emoji prefixes (emoji and :emoji: format)
• ❌ Missing emoji prefix (fails with helpful error message)
• ❌ Invalid emoji prefix (fails with correct guidance)
• ✅ Input validation (500 char length limit, safe output handling)

Which issue(s) this PR fixes

NONE

Special notes for your reviewer

The workflow checks out the base branch (via ref: ${{ github.base_ref }}) to run the verification script, ensuring only trusted code executes.

Does this PR introduce a user-facing change?

The PR verifier workflow now uses a local shell script instead of the deprecated kubebuilder-release-tools Docker action. PR title requirements are unchanged - contributors must still use emoji prefixes as documented in CONTRIBUTING.md.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.67%. Comparing base (353ed60) to head (01f9cf8).
⚠️ Report is 324 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4972      +/-   ##
==========================================
+ Coverage   66.80%   69.67%   +2.87%     
==========================================
  Files         230      251      +21     
  Lines       16602    15654     -948     
==========================================
- Hits        11091    10907     -184     
+ Misses       4808     3873     -935     
- Partials      703      874     +171     

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[justaugustus]

@spencerschrock @AdamKorcz — need a review, as this failure currently blocks all PRs.