Bump reviewdog/action-languagetool from 1.9 to 1.20

Bumps [reviewdog/action-languagetool](https://github.com/reviewdog/action-languagetool) from 1.9 to 1.20.
- [Release notes](https://github.com/reviewdog/action-languagetool/releases)
- [Commits](reviewdog/action-languagetool@v1.9...v1.20)

---
updated-dependencies:
- dependency-name: reviewdog/action-languagetool
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

.github/workflows/reviewdog.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v3
-      - uses: reviewdog/action-languagetool@v1.9
+      - uses: reviewdog/action-languagetool@v1.20
         with:
           github_token: ${{ secrets.PAT }}
           level: info