Added user agent related to nim backdoor used by APT-Q-39

[MalGamy]

Summary of the Pull Request

This PR adds new user agent related to nim backdoor used by APT-Q-39

Changelog

update: add new user agent related to nim backdoor used by APT-Q-39

Example Log Event

N/A

Fixed Issues

N/A

SigmaHQ Rule Creation Conventions

• If your PR adds new rules, please consider following and applying these [conventions]

[github-actions]

Welcome @MalGamy 👋

It looks like this is your first pull request on the Sigma rules repository!

Please make sure to read the SigmaHQ conventions document to make sure your contribution is adhering to best practices and has all the necessary elements in place for a successful approval.

Thanks again, and welcome to the Sigma community! 😃

[nasbench]

Hey @MalGamy thanks for opening this first PR.

Unfortunately we can't use this UA as its used by legitimate browsers as well. See this ref

Closing this as this reason. Thanks once again.