Add the .not() operator to the MergeRequestFilter

[KoCoder]

Returns merge requests that do not match the parameters supplied. Works with labels, milestone, author_id, author_username, assignee_id, assignee_username, reviewer_id, reviewer_username, my_reaction_emoji

[ritikverma2000]

Hi @KoCoder I would like to work on this issue can you assign me this issue ?
Also give me some example of the issue which you are facing.

[KoCoder]

Since I'm not a maintainer of this Repository, I can't assign you to this issue. Anyways feel free to implement this on your own fork and then create a PR.

[jmini]

I thought I already did it, but the open MR is adding the not support in the EpicFilter: #1005

Usage of the not attribute is described here:
https://docs.gitlab.com/ee/api/merge_requests.html#list-merge-requests

I welcome a PR for this issue.
@ritikverma2000 feel free to work on it.