drop cicd workflow from release branch; add execution on tags

running on the release branch is causing duplicate execution, which is
especially unnecessary since every merge to release branch is
accompanied by a tag

Author: troyready

.github/workflows/cicd.yml

@@ -5,7 +5,8 @@ on:
   push:
     branches:
       - master
-      - release
+    tags:
+      - v*.*.*
 
 env:
   AWS_DEFAULT_REGION: us-east-1