ci: enable pull_request workflow trigger (#178)

Author: edeckers

.github/workflows/ci.yml

@@ -1,5 +1,10 @@
 name: Build and test
-on: push
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+      - develop
 
 env: 
   node-version: 12