Add checking out from forked head

.github/workflows/acceptance-test.yml

@@ -29,6 +29,26 @@ jobs:
     steps:
       - name: Base checkout
         uses: actions/checkout@v4
+        if: |
+          github.event_name != 'repository_dispatch' &&
+          (
+            github.ref == 'refs/heads/main' || 
+            (
+              github.event_name == 'pull_request' && 
+              github.event.pull_request.head.repo.full_name == github.repository
+            )
+          )
+      - name: Fork based /ok-to-test checkout
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.client_payload.pull_request.head.sha }}
+        if: |
+          github.event_name == 'repository_dispatch' &&
+          github.event.client_payload.slash_command.args.named.sha != '' &&
+          contains(
+            github.event.client_payload.pull_request.head.sha,
+            github.event.client_payload.slash_command.args.named.sha
+          )
       - name: Launch 1Password Connect instance
         if: ${{ matrix.auth == 'connect' }}
         env: