Catch exception if close() in exception manager, throw another except…

[pprados]

Given this is a project maintained by volunteers, please read this template to not waste your time, or ours! 😁 -->

Summary

If some scenario, to close the program, the code catch en exception, and try to close itself. But, if this close generate and exception, the code crash with a stacktrace.

    async def __aiter__(self) -> typing.AsyncIterator[bytes]:
        try:
            async for part in self._stream:
                yield part
        except BaseException as exc:
            try:
                await self.aclose()
            except BaseException:
                pass
            raise exc from None

Checklist

• I understand that this PR may be closed in case there was no previous discussion. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.