Add weekly OSV dependency audit

.gitea/workflows/dependency-audit.yml

@@ -0,0 +1,21 @@
+name: Weekly OSV dependency audit
+
+on:
+  schedule:
+    # Runs every Monday. Change the minute to stagger repositories.
+    - cron: "41 3 * * 1"
+  workflow_dispatch:
+
+jobs:
+  dependency-audit:
+    runs-on: linux-arm64
+    timeout-minutes: 20
+
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+
+      - name: Scan dependencies for known vulnerabilities
+        uses: docker://ghcr.io/google/osv-scanner:v2
+        with:
+          args: scan source --recursive .