fix(ci): remove unnecessary PR action as we combined issues and prs into one board

.github/workflows/prs.yml

@@ -1,16 +0,0 @@
-name: Add pull requests to Tiptap project
-
-on:
-  pull_request:
-    types:
-      - opened
-
-jobs:
-  add-to-project:
-    name: Add pull request to project
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/add-to-project@main
-        with:
-          project-url: ${{ secrets.ADD_TO_PROJECT_URL }}
-          github-token: ${{ secrets.ADD_TO_PROJECT_PAT }}