Fix a typo in a docstring

pythonFiles/experimental/testlauncher.py

@@ -39,7 +39,7 @@ def exclude_current_file_from_debugger():
 def run(cwd, testRunner, args):
     """Runs the test
     cwd -- the current directory to be set
-    testRuner -- test runner to be used `pytest` or `nose`
+    testRunner -- test runner to be used `pytest` or `nose`
     args -- arguments passed into the test runner
     """