Removed s390x, linux/arm platform as docker build was crashing (#8121)

Co-authored-by: Carlos Tadeu Panato Junior <ctadeu@gmail.com>

.github/workflows/ci.yaml

@@ -256,7 +256,7 @@ jobs:
       pull-requests: read  # for dorny/paths-filter to read pull requests
     runs-on: ubuntu-latest
     env:
-      PLATFORMS: linux/amd64
+      PLATFORMS: linux/amd64,linux/arm64
     steps:
       - name: Checkout
         uses: actions/checkout@629c2de402a417ea7690ca6ce3f33229e27606a5 # v2
@@ -280,6 +280,8 @@ jobs:
               - 'images/httpbin/**'
             kube-webhook-certgen:
               - 'images/kube-webhook-certgen/**'
+            ext-auth-example-authsvc:
+              - 'images/ext-auth-example-authsvc/**'
 
       - name: custom-error-pages image build
         if: ${{ steps.filter-images.outputs.custom-error-pages == 'true' }}
@@ -309,6 +311,10 @@ jobs:
         if: ${{ steps.filter-images.outputs.kube-webhook-certgen == 'true' }}
         run: |
           cd images/kube-webhook-certgen && make build
+      - name: ext-auth-example-authsvc
+        if: ${{ steps.filter-images.outputs.ext-auth-example-authsvc == 'true' }}
+        run: |
+          cd images/ext-auth-example-authsvc && make build
 
   test-image:
     permissions: