Update build.yml to trigger GHA checks only on pushes to main and PRs

Closes #112

.github/workflows/build.yml

@@ -14,7 +14,16 @@
 ## JBIJPPTPL
 
 name: Build
-on: [push, pull_request]
+on:
+  # Trigger the workflow on pushes to only the 'main' branch
+  # (this avoids duplicate checks being run e.g. for dependabot pull requests)
+  push:
+    branches:
+      - main
+  # Trigger the workflow on any pull request
+  pull_request:
+
+
 jobs:
 
   # Run Gradle Wrapper Validation Action to verify the wrapper's checksum