codeql: bump actions/cache from 4 to 5

Bumps [actions/cache](https://github.com/actions/cache) from 4 to 5.
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](https://github.com/actions/cache/compare/v4...v5)

updated-dependencies:
- dependency-name: actions/cache
  dependency-version: '5'
  dependency-type: direct:production
  update-type: version-update:semver-major

Originally-authored-by: dependabot[bot] <support@github.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

.github/workflows/coverity.yml

@@ -98,7 +98,7 @@ jobs:
       # A cache miss will add ~30s to create, but a cache hit will save minutes.
       - name: restore the Coverity Build Tool
         id: cache
-        uses: actions/cache/restore@v4
+        uses: actions/cache/restore@v5
         with:
           path: ${{ runner.temp }}/cov-analysis
           key: cov-build-${{ env.COVERITY_LANGUAGE }}-${{ env.COVERITY_PLATFORM }}-${{ steps.lookup.outputs.hash }}
@@ -141,7 +141,7 @@ jobs:
           esac
       - name: cache the Coverity Build Tool
         if: steps.cache.outputs.cache-hit != 'true'
-        uses: actions/cache/save@v4
+        uses: actions/cache/save@v5
         with:
           path: ${{ runner.temp }}/cov-analysis
           key: cov-build-${{ env.COVERITY_LANGUAGE }}-${{ env.COVERITY_PLATFORM }}-${{ steps.lookup.outputs.hash }}