Update CI

.github/workflows/ci.yml

@@ -21,6 +21,20 @@ permissions:
   pull-requests: write
 
 jobs:
+  changes:
+    runs-on: ubuntu-latest
+    permissions:
+      pull-requests: read
+    outputs:
+      apps: ${{ steps.filter.outputs.changes }}
+    steps:
+    - uses: dorny/paths-filter@v3
+      id: filter
+      with:
+        filters: |
+          game-2048: src/game-2048
+          cow-demo: src/cow-demo
+          rancher-helloworld: src/rancher-helloworld
   code-check:
     runs-on: ubuntu-latest
     steps:
@@ -65,9 +79,10 @@ jobs:
         if: steps.list-changed.outputs.changed == 'true'
         run: ct lint --target-branch ${{ github.event.repository.default_branch }}
   image-scan:
+    needs: changes
     strategy:
       matrix:
-        app: [game-2048, cow-demo, rancher-helloworld]
+        app: ${{ fromJSON(needs.changes.outputs.apps) }}
     runs-on: ubuntu-latest
     steps:
       - name: Checkout source code