Fix review comment.

Author: sellakumaran

libraries/microsoft-agents-a365-tooling/microsoft_agents_a365/tooling/utils/utility.py

@@ -139,7 +139,7 @@ def get_ppapi_token_scope():
     envScope = os.getenv("MCP_PLATFORM_AUTHENTICATION_SCOPE", "")
 
     if envScope:
-        return envScope
+        return [envScope]
 
     if environment == "development":
         return [PPAPI_TEST_TOKEN_SCOPE + "/.default"]