skipBuildTagsForGitHubPullRequests when the PR is a fork (#2770)

Author: satvu

eng/ci/public-build.yml

@@ -55,6 +55,10 @@ extends:
         image: 1es-windows-2022
         os: windows
 
+    settings:
+      # PR's from forks do not have sufficient permissions to set tags.
+      skipBuildTagsForGitHubPullRequests: ${{ variables['System.PullRequest.IsFork'] }}
+
     stages:
     - stage: Test