ci: Use MetaMask/action-is-release@v2 for release check workflow

[Mrtenz]

Explanation

The changes needed for the release check are now included in the stable version of MetaMask/action-is-release, so we can use that instead.

References

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed, highlighting breaking changes as necessary
• I've prepared draft pull requests for clients and consumer packages to resolve any breaking changes

---

Note

Update workflow to use MetaMask/action-is-release@v2 instead of a pinned commit for release detection.

^{Written by Cursor Bugbot for commit b7c4a07. This will update automatically on new commits. Configure here.}