added build date to headers

.gitea/workflows/build.yml

@@ -20,6 +20,11 @@ jobs:
       - name: Install
         run: npm ci
 
+      - name: Inject build date
+        run: |
+          BUILD_DATE=$(date -u +"%Y-%m-%d %H:%M:%S UTC")
+          sed -i "s/__BUILD_DATE__/$BUILD_DATE/" index.html
+
       - name: Build
         run: npm run build