ci: add pr trigger types (#41)

Signed-off-by: Michael Beemer <[email protected]>

Author: beeme1mr

.github/workflows/build.yml

@@ -6,10 +6,11 @@
 name: "Build, lint, and test"
 
 on:
-  push:
-    branches:
-      - main
   pull_request:
+    types:
+      - opened
+      - synchronize
+      - reopened
     branches:
       - main