Update Deploy Preview to use pull_request_target

Access to secrets is not possible with PR from fork. 

Caution will need to be had around allowing commits to this yml file in the future.

Not that secrets should not be available to code itself (actions with params only).

.github/workflows/deploy-preview.yml

@@ -1,6 +1,6 @@
 name: 'Preview Deployment'
 on:
-  pull_request:
+  pull_request_target:
     branches:
       - master
 
@@ -35,9 +35,6 @@ jobs:
       - name: Deploy to Cloudflare
         id: deploy
         uses: cloudflare/wrangler-action@v3
-        env:
-          CLOUDFLARE_API_TOKEN: ${{ secrets.CLOUDFLARE_API_TOKEN }}
-          CLOUDFLARE_ACCOUNT_ID: ${{ secrets.CLOUDFLARE_ACCOUNT_ID }}
         with:
           apiToken: ${{ secrets.CLOUDFLARE_API_TOKEN }}
           accountId: ${{ secrets.CLOUDFLARE_ACCOUNT_ID }}