code: implement retry mechanism with requests

[ankan17]

Due to unstable network, the API call may not go through while getting the repositories of a user in the get_repositories function defined in utils.py. We need a retry mechanism to try multiple times to get the repositories and handle the error gracefully even if the network is not available and repositories are not saved. A good solution is provided here: https://www.peterbe.com/plog/best-practice-with-retries-with-requests.