fix pr-preview to allow for external contributor previews with approval (#414)

Author: Ethan-Arrowood

.github/workflows/pr-preview.yaml

@@ -1,7 +1,7 @@
 name: Deploy PR Preview
 
 on:
-  pull_request:
+  pull_request_target:
     types: [opened, synchronize, reopened, closed]
 
 # Cancel previous runs when new commits are pushed to the PR
@@ -14,6 +14,7 @@ jobs:
     name: Deploy PR Preview
     runs-on: ubuntu-latest
     if: github.event.action != 'closed'
+    environment: preview # Requires manual approval for fork PRs
     permissions:
       pull-requests: write
       deployments: write