Update unit test workflow to use pull request source code (#3072)

Author: Greg Weresch

.github/workflows/tests-unit.yml

@@ -7,7 +7,7 @@ on:
       - "v9.*"
       - "v8.*"
       - "v7.*"
-  pull_request_target:
+  pull_request:
     branches:
       - main
       - v9