Set fetch-depth for public PR check to 0/all (#3492)

That way the Bootstrap script will actually be able to find a manifest.

.github/workflows/pull_request_checks.yml

@@ -15,7 +15,7 @@ jobs:
         uses: actions/checkout@v4
         with:
           clean: true
-          fetch-depth: 1
+          fetch-depth: 0
           persist-credentials: false
       - name: Setup .NET
         uses: actions/setup-dotnet@v5