chore: bump actions/github-script from 7 to 9

Bumps [actions/github-script](https://github.com/actions/github-script) from 7 to 9.
- [Release notes](https://github.com/actions/github-script/releases)
- [Commits](https://github.com/actions/github-script/compare/v7...v9)

---
updated-dependencies:
- dependency-name: actions/github-script
  dependency-version: '9'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/merge-conflict-detector.yml

@@ -27,7 +27,7 @@ jobs:
           fetch-depth: 0
 
       - name: Ensure label exists
-        uses: actions/github-script@v7
+        uses: actions/github-script@v9
         with:
           script: |
             const LABEL = 'has-conflicts';
@@ -46,7 +46,7 @@ jobs:
             }
 
       - name: Check PRs and label conflicts
-        uses: actions/github-script@v7
+        uses: actions/github-script@v9
         with:
           script: |
             const LABEL = 'has-conflicts';