stop duplicate gate workflow runs

The integration tests is triggered twice on force pushes to master.
We only want it to run once.

* trigger integration tests on merges to master branch
* trigger integration tests on creation of branches from PRs
* do not trigger integration tests twice

only run integration tests once

.github/workflows/gate.yaml

@@ -7,7 +7,7 @@ on:
     types:
       - completed
     branches:
-      - '*'
+      - master
 
 jobs:
   integration-tests: