ci: add conventional commit check

Signed-off-by: Richard Steinmetz <richard@steinmetz.cloud>

.github/workflows/conventional_commits.yml

@@ -0,0 +1,17 @@
+# SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+name: Conventional Commits
+
+on:
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  build:
+    name: Conventional Commits
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: webiny/action-conventional-commits@v1.3.0