Bump fourmolu/fourmolu-action from 5 to 9

Bumps [fourmolu/fourmolu-action](https://github.com/fourmolu/fourmolu-action) from 5 to 9.
- [Release notes](https://github.com/fourmolu/fourmolu-action/releases)
- [Changelog](https://github.com/haskell-actions/run-fourmolu/blob/master/CHANGELOG.md)
- [Commits](haskell-actions/run-fourmolu@v5...v9)

---
updated-dependencies:
- dependency-name: fourmolu/fourmolu-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/linting.yml

@@ -11,7 +11,7 @@ jobs:
     steps:
     - uses: actions/checkout@v2
 
-    - uses: fourmolu/fourmolu-action@v5
+    - uses: fourmolu/fourmolu-action@v9
       with:
         pattern: |
           app/**/*.hs