Bump MySQL test version from 8.0.39 to 8.0.42

[Claude]

Updates MySQL version references from 8.0.39 to 8.0.42 in GitHub Actions workflow test matrices to match current Aurora version as of #42120.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 66.45%. Comparing base (fc2339e) to head (b1dca08).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #42122   +/-   ##
=======================================
  Coverage   66.45%   66.45%           
=======================================
  Files        2516     2516           
  Lines      201965   201976   +11     
  Branches     8921     8921           
=======================================
+ Hits       134225   134233    +8     
- Misses      55595    55599    +4     
+ Partials    12145    12144    -1     

Flag	Coverage Δ
backend	68.25% <ø> (+<0.01%)	⬆️
backend-activity	86.35% <ø> (ø)

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[iansltx]

@claude Look at #40892 for inspiration. See if we are missing anything here.

[claude]

Claude Code Review

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[Copilot]

Pull request overview

Updates the GitHub Actions Go test workflows to run the “extended MySQL coverage” matrix against MySQL 8.0.42 instead of 8.0.39, and reflects that change in the user-visible changes entry.

Changes:

• Bumped the extended MySQL test matrix from mysql:8.0.39 to mysql:8.0.42 in the Go test workflow.
• Bumped the extended MySQL test matrix from mysql:8.0.39 to mysql:8.0.42 in the activity Go test workflow.
• Updated the changes/ entry to reflect the new MySQL version under test.

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 1 comment.

File	Description
changes/bump-mysql	Updates the changelog entry to reference 8.0.42 instead of 8.0.39.
.github/workflows/test-go.yaml	Updates the nightly “extended MySQL coverage” matrix to use mysql:8.0.42.
.github/workflows/test-go-activity.yaml	Updates the nightly “extended MySQL coverage” matrix to use mysql:8.0.42.

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[Copilot]

The changes entry reads “tests MySQL against to …” which is grammatically incorrect and a bit confusing. Consider rewording to “tests MySQL against 9.5.0 (unchanged), 8.4.8, 8.0.44, and 8.0.42.”

Suggested change

	* Revised which versions Fleet tests MySQL against to 9.5.0 (unchanged), 8.4.8, 8.0.44, and 8.0.42.
	* Revised which versions Fleet tests MySQL against 9.5.0 (unchanged), 8.4.8, 8.0.44, and 8.0.42.