adjust git workflow (#186)

Author: jcstorms1

.github/workflows/build.yml

@@ -1,6 +1,10 @@
 name: build
 
-on: [push, pull_request]
+on:
+  push:
+    branches:
+      - "main"
+  pull_request:
 
 jobs:
   lint:
@@ -115,4 +119,4 @@ jobs:
       - name: Send a failure metric
         env:
           DD_API_KEY: ${{ secrets.DD_API_KEY }}
-        run: ./scripts/send_status_metric.sh 1 $DD_API_KEY
+        run: ./scripts/send_status_metric.sh 1 $DD_API_KEY