Fix indentation of a comment in buffer.py (#371)

Signed-off-by: Chris Lalancette <[email protected]>

Author: clalancette

tf2_ros_py/tf2_ros/buffer.py

@@ -106,7 +106,7 @@ def _call_new_data_callbacks(self) -> None:
         with self._callbacks_lock:
             for callback in self._new_data_callbacks:
                 callback()
-        # Remove callbacks after to avoid modifying list being iterated on
+            # Remove callbacks after to avoid modifying list being iterated on
             for callback in self._callbacks_to_remove:
                 self._new_data_callbacks.remove(callback)
             self._callbacks_to_remove.clear()