Adding docker/metadata-action for auto-tagging

- *Should* auto-tag based on GitHub branch and tag
- Fixes #872

.github/workflows/ci.yml

@@ -133,6 +133,12 @@ jobs:
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v1
 
+      - name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v4
+        with:
+          images: jaedb/iris
+
       - name: Login to DockerHub
         uses: docker/login-action@v1 
         with:
@@ -143,4 +149,5 @@ jobs:
         uses: docker/build-push-action@v2
         with:
           push: true
-          tags: jaedb/iris:latest
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}