feat(build): use pull_request_target for datahub-wheels (#12722)

Author: hsheth2

.github/workflows/python-build-pages.yml

@@ -8,7 +8,7 @@ on:
       - "metadata-ingestion/**"
       - "metadata-ingestion-modules/**"
       - "metadata-models/**"
-  pull_request:
+  pull_request_target:
     branches:
       - "**"
     paths:
@@ -38,7 +38,11 @@ jobs:
           distribution: "zulu"
           java-version: 17
       - uses: gradle/actions/setup-gradle@v4
-      - uses: acryldata/sane-checkout-action@v3
+      - uses: actions/checkout@v4
+        # Note: not using acryldata/sane-checkout-action because this is a
+        # pull_request_target event, and hence requires `ref`.
+        with:
+          ref: ${{ github.event.pull_request.base.sha }}
       - uses: actions/setup-python@v5
         with:
           python-version: "3.10"