added C# to run_tests.py
diff --git a/src/csharp/.gitignore b/src/csharp/.gitignore
index d35ff63..4f4cd1f 100644
--- a/src/csharp/.gitignore
+++ b/src/csharp/.gitignore
@@ -2,3 +2,4 @@
 test-results
 packages
 Grpc.v12.suo
+TestResult.xml