Add pull request handling for main

Author: michaelnordmeyer

.github/workflows/jekyll-theme.yml

@@ -4,6 +4,8 @@ on:
   # Runs on pushes targeting the default branch
   push:
     branches: ["main"]
+  pull_request:
+    branches: ["main"]
 
   # Allows you to run this workflow manually from the Actions tab
   workflow_dispatch: