Use public ECR zot image

Per Amazon best security practices, we switched to using a version of
project zot hosted on public ECR instead of ghcr.io.

Signed-off-by: David Son <davbson@amazon.com>

integration/util_test.go

@@ -75,7 +75,7 @@ const (
 	// Registry images to use in the test infrastructure. These are not intended to be used
 	// as images in the test itself, but just when we're setting up docker compose.
 	oci10RegistryImage = "registry:soci_test"
-	oci11RegistryImage = "ghcr.io/project-zot/zot-linux-" + runtime.GOARCH + ":v2.0.1"
+	oci11RegistryImage = "public.ecr.aws/soci-workshop-examples/zot:v2.0.3-" + runtime.GOARCH
 )
 
 // Commonly used CLI commands