Fix GH actions duplicated builds

.github/workflows/build.yml

@@ -1,5 +1,14 @@
 name: "Build and Report Generation"
-on: [push, pull_request]
+on:
+  push:
+  pull_request:
+    branches:
+      # Branches from forks have the form 'user:branch-name' so we only run
+      # this job on pull_request events for branches that look like fork
+      # branches. Without this we would end up running this job twice for non
+      # forked PRs, once for the push and then once for opening the PR.
+      # Taken from https://github.uint.cloudmunity/t/how-to-trigger-an-action-on-push-or-pull-request-but-not-both/16662/10
+      - '**:**'
 
 jobs:
   test: