Remove commented lines and update docstring

The _get_new_writer function was previously calling
`self._writer.close()`. The `self.writer` function is already being
closed in the call stack. Due to `self.writer` and `self._writer`
being linked, there was an error that the IO file was closed.

The `self._writer.close()` was commented out in a prior commit as a
proposal for the change. That comment is now removed. The docstring
is updated.

Author: j-c-cook

can/io/logger.py

@@ -208,17 +208,17 @@ def on_message_received(self, msg: Message) -> None:
         self.writer.on_message_received(msg)
 
     def _get_new_writer(self, filename: StringPathLike) -> FileIOMessageWriter:
-        """Instantiate a new writer after stopping the old one.
+        """Instantiate a new writer.
+
+        .. note::
+            The :attr:`self.writer` should be closed prior to calling this function.
 
         :param filename:
             Path-like object that specifies the location and name of the log file.
             The log file format is defined by the suffix of `filename`.
         :return:
             An instance of a writer class.
         """
-        # Close the old writer first
-        # if self._writer is not None:
-        #     self._writer.stop()
 
         logger = Logger(filename, *self.writer_args, **self.writer_kwargs)
         if isinstance(logger, FileIOMessageWriter):