ci: fix typo

Author: clafoutis42

.github/workflows/build-push.yaml

@@ -53,9 +53,9 @@ jobs:
         with:
           load: true
           push: true
-          platform:
-            - linux/amd64
-            - linux/arm64
+          platforms:
+            - "linux/amd64"
+            - "linux/arm64"
           tags: ${{ steps.login-ecr-public.outputs.registry }}/${{ vars.ECS_REGISTRY_ALIAS }}/${{ vars.ECS_REPOSITORY_NAME }}:${{ steps.extract_refs.outputs.tag }}
           cache-from: type=local,src=/tmp/.buildx-cache
           cache-to: type=local,dest=/tmp/.buildx-cache-new