fix: check Client._http is not a string before logout

[Damego]

About

There is case when exception was raised before http client was set.

Traceback (most recent call last):
  File "/config/.local/lib/python3.10/site-packages/interactions/client/bot.py", line 202, in start
    self._loop.run_until_complete(self._logout())
  File "/usr/lib/python3.10/asyncio/base_events.py", line 649, in run_until_complete
    return future.result()
  File "/config/.local/lib/python3.10/site-packages/interactions/client/bot.py", line 1623, in _logout
    await self._http._req.close()
AttributeError: 'str' object has no attribute '_req'

Checklist

• The pre-commit code linter has been run over all edited files to ensure the code is linted.
• I've ensured the change(s) work on 3.8.6 and higher.
• I have added the versionadded, versionchanged and deprecated to any new or changed user-facing function I committed.

Pull-Request specification

I've made this pull request: (check all that apply)

• For the documentation
• To add a new feature
• As a general enhancement
• As a refactor of the library/the library's code
• To fix an existing bug
• To resolve #ISSUENUMBER

This is:

• A breaking change