Bump geekyeggo/delete-artifact from 5 to 6

Bumps [geekyeggo/delete-artifact](https://github.com/geekyeggo/delete-artifact) from 5 to 6.
- [Release notes](https://github.com/geekyeggo/delete-artifact/releases)
- [Changelog](https://github.com/GeekyEggo/delete-artifact/blob/main/CHANGELOG.md)
- [Commits](https://github.com/geekyeggo/delete-artifact/compare/v5...v6)

---
updated-dependencies:
- dependency-name: geekyeggo/delete-artifact
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/ci_build_major_branch_keymap.yml

@@ -166,7 +166,7 @@ jobs:
           truncate --size='<960K' $GITHUB_STEP_SUMMARY || true
 
       - name: Delete temporary build artifacts
-        uses: geekyeggo/delete-artifact@v5
+        uses: geekyeggo/delete-artifact@v6
         with:
           name: |
             firmware-${{ inputs.keymap }}-*