#3: Add real-time alerts for new issues

[iamnovichek]

1. Create a new branch named feat/add-real-time-alerts-for-new-issues
2. Add scheduled celery tasks that will check every predefined number of seconds if there're some new issues for the repository our user subscribed to.
3. If there is new issues, this user will be notified.

[UzNaZ]

Dear Cucina,

I trust this message finds you well. I am reaching out to kindly request assignment to the issue in this repository. I would be delighted to contribute my efforts toward its resolution and am prepared to approach the task with utmost dedication.

Please do let me know if I may be of service in this regard.

Yours sincerely,
UzNaZ

[djeck1432]

@UzNaZ Any updates, you will be unassign for this issue if you are not creating PR next few hours