Makefile: add simple image-push target

And use it in workflow.

.github/workflows/publish_to_dockerhub.yml

@@ -79,4 +79,6 @@ jobs:
 
       - name: Push image with 'latest' tag to registry
         if: ${{ github.event_name == 'release' && github.event.release.target_commitish == 'master' }}
-        run: make image-push-latest
+        run: make image-push
+        env:
+          HUB_TAG: latest

Makefile

@@ -66,6 +66,11 @@ image:
 		-f Dockerfile \
 		-t $(HUB_IMAGE):$(HUB_TAG) .
 
+# Push Docker image to the hub
+image-push:
+	@echo "⇒ Publish image"
+	@docker push $(HUB_IMAGE):$(HUB_TAG)
+
 # Build dirty Docker image
 dirty-image:
 	@echo "⇒ Build NeoFS HTTP Gateway dirty docker image "