Update synapse build action

.forgejo/workflows/build-synapse.yaml

@@ -1,11 +1,12 @@
 on:
   push:
     paths:
-      - containers/synapse/Containerfile
+      - containers/synapse/*
+      - .forgejo/workflows/build-synapse.yaml
   schedule:
     - cron: '0 12 */7 * *'
 jobs:
-  build-container:
+  build-synapse:
     runs-on: docker
     container:
       image: library/docker:dind
@@ -16,7 +17,7 @@ jobs:
       - name: build container image
         uses: docker/build-push-action@v4
         with:
-          file: Containerfile
+          file: containers/synapse/Containerfile
           tags: git.janky.solutions/jankysolutions/infra/synapse:latest
           platforms: linux/amd64
           push: true