Change github action for docker latest image

.github/workflows/README.md

@@ -7,11 +7,11 @@
 ## Workflow
 
 - On each pull request, we are triggering `cargo test`.
-- On each commit on master, we are building the latest docker image.
 - On each tag, we are building:
     - the tagged docker image
     - the binaries for MacOS, Ubuntu, and Windows
     - the debian package
+- On each stable release, we are build the latest docker image.
 
 ## Problems
 

.github/workflows/publish-docker-latest.yml

@@ -1,8 +1,8 @@
 ---
 on:
   push:
-    branches:
-      - master
+    tags:
+      - 'v[0-9]+.[0-9]+.[0-9]+'
 
 name: Publish latest image to Docker Hub