Modify weekly pulumi upgrade action to run acceptance tests in PR (#1313

)

Previously the weekly pulumi upgrade couldn't auto-merge because it used
the built-in action access token for creating the PR. That default GH
action user doesn't have the necessary access rights (i.e. is not a
member of pulumi) to run acceptance tests.

This change makes the gh cli use the pulumi bot token.

.github/workflows/weekly-pulumi-update.yml

@@ -87,7 +87,7 @@ jobs:
     - name: pull-request
       if: steps.gomod.outputs.changes != 0
       env:
-        GH_TOKEN: ${{ github.token }}
+        GH_TOKEN: ${{ secrets.PULUMI_BOT_TOKEN }}
       run: |
         gh pr create --title "Update pulumi/pulumi version to $PULUMI_VERSION" --body "Upgrading pulumi/pkg and pulumi/sdk to version $PULUMI_VERSION."
     - name: Enable auto-merge