ci: add commitlint action

To check that commits are according to the Conventional Commits spec.
https://www.conventionalcommits.org/en/v1.0.0/

.github/workflows/lint-pr.yml

@@ -13,10 +13,7 @@ jobs:
           fetch-depth: 0
 
       - run: >-
-          npx
+          npx commitlint
-          --package @commitlint/cli
-          --package @commitlint/config-conventional
-          commitlint
           -g .github/workflows/commitlint.config.js
           --from ${{ gitea.event.pull_request.base.sha }}
           --to ${{ gitea.event.pull_request.head.sha }}