Bump README.md for v1.4.0 release

Author: boomper-bot[bot]

README.md

@@ -14,7 +14,7 @@ steps:
   - wait: ~
     continue_on_failure: true
   - plugins:
-      junit-annotate#v1.3.0:
+      junit-annotate#v1.4.0:
         artifacts: tmp/junit-*.xml
 ```
 
@@ -66,7 +66,7 @@ To test your plugin in your builds prior to opening a pull request, you can refe
 steps:
   - label: Annotate
     plugins:
-      YourGithubHandle/junit-annotate#sha:
+      YourGithubHandle/junit-annotate#v1.4.0:
         ...
 ```