don't build docker images when not needed

.github/workflows/docker.yaml

@@ -3,6 +3,8 @@ name: Build haze images
 on:
   push:
     branches: ['main']
+    paths:
+      - 'images/**'
 
 permissions:
   contents: read
@@ -22,6 +24,15 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v3
 
+      - uses: dorny/paths-filter@4067d885736b84de7c414f582ac45897079b0a78 #v2.11.1
+        id: changes
+        with:
+          filters: |
+            php:
+              - 'images/php/**'
+            haze:
+              - 'images/haze/**'
+
       - name: Log in to the Container registry
         uses: docker/login-action@65b78e6e13532edd9afa3aa52ac7964289d1a9c1
         with:
@@ -32,6 +43,7 @@ jobs:
         uses: docker/setup-buildx-action@v2
 
       - name: Build php image
+        if: steps.changes.outputs.php == 'true'
         uses: docker/build-push-action@f2a1d5e99d037542a71f64918e516c093c6f3fc4
         with:
           context: "images/php"
@@ -44,6 +56,7 @@ jobs:
           cache-to: type=gha,mode=max
 
       - name: Build haze image
+        if: steps.changes.outputs.haze == 'true'
         uses: docker/build-push-action@f2a1d5e99d037542a71f64918e516c093c6f3fc4
         with:
           context: "images/haze"