Add missing whitespace

Author: bxsx

Lib/test/test_calendar.py

@@ -936,7 +936,7 @@ def captured_stderr_with_buffer(self):
         finally:
             sys.stderr.flush()
             sys.stderr.buffer.seek(0, 0)
-            sys.stderr= orig_stderr
+            sys.stderr = orig_stderr
 
     def run_cli_ok(self, *args):
         with self.captured_stdout_with_buffer() as stdout: