workflow docker: set provenance=false to avoid multiple manifests

https://stackoverflow.com/a/77207574/6565736

Author: dschofie

.github/workflows/dockerimage.yml

@@ -50,4 +50,5 @@ jobs:
           docker buildx build \
             --platform linux/arm/v7,linux/arm64/v8,linux/amd64 \
             --tag $REGISTRY/$REGISTRY_ALIAS/$REPOSITORY:$IMAGE_TAG \
+            --provenance=false
             --push .