Fix AttributeError on closing of django runserver

[slimadvies]

When closing Django runserver, valkey client consistently throws the AttributeError in the function del

This patch fixes that problem

Pull Request check-list

• Do tests and lints pass with this change?
• Do the CI tests pass with this change (enable it first in your forked repo and wait for the github action build to finish)?
• Is the new or changed code fully tested?
• Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?
• Is there an example added to the examples folder (if applicable)?

Description of change

[mkmkme]

Hey! Thanks for your contribution.
The code unfortunately doesn't look like a fix but rather like a workaround for an existing problem.
Could you please create an issue with the detailed description of the problem? What exactly do you do to get this exception thrown, what version you're using and what is the stack trace?

Thank you in advance!

[slimadvies]

Issue #158

[mkmkme]

Thank you! I'll have to close this PR in order to fix the root cause of the issue.