ci: add zizmor workflow audit

.github/dependabot.yml

@@ -7,6 +7,8 @@ updates:
       day: sunday
       time: '22:00'
       timezone: Etc/UTC
+    cooldown:
+      default-days: 7
     open-pull-requests-limit: 5
     groups:
       minor-and-patch:

.github/workflows/lint-pr-title.yml

@@ -7,9 +7,15 @@ on:
       - edited
       - synchronize
 
+permissions:
+  contents: read
+
 jobs:
   lint:
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      pull-requests: read
     steps:
       - uses: amannn/action-semantic-pull-request@e32d7e603df1aa1ba07e981f2a23455dee596825 # v5
         env:

.github/workflows/zizmor.yml

@@ -0,0 +1,31 @@
+name: Zizmor
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    types:
+      - opened
+      - synchronize
+      - reopened
+  schedule:
+    # Weekly: online audits (known-vulnerable actions, impostor commits) can
+    # start failing without a code change.
+    - cron: '0 4 * * 1'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+# Grouped per event, so a push to the default branch can never cancel or
+# displace the weekly run. Running pull request runs are cancelled by newer
+# ones; for other events GitHub still replaces a queued run with a newer one.
+concurrency:
+  group: zizmor-${{ github.event_name }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
+jobs:
+  zizmor:
+    name: Zizmor
+    uses: owncloud/reusable-workflows/.github/workflows/zizmor.yml@main