Fix indentation in README.md sample code

Author: howieleung

sdk/ai/azure-ai-projects/tests/samples/README.md

@@ -43,7 +43,7 @@ class TestSamples(AzureRecordedTestCase):
         executor.validate_print_calls_by_llm(
             instructions=agent_tools_instructions,
             project_endpoint=kwargs["azure_ai_projects_tests_project_endpoint"],
-        )        
+        )
 ```
 
 ### Async example