Resolve CORS localhost issues

[rob-3]

I added some CORS headers that I believe will get requests from localhost to work, which will make testing the frontend easier.

Checklist:

• [ ] Add tests that demonstrate the correct behavior of the change. Tests should fail without the change.
• [ ] Add or update the relevant docs.
• [ ] Add an entry in CHANGELOG.md summarizing the change.
• [ ] Run tests, with no tests failed.

[github-actions[bot]]

File	Coverage
All files	73%	:x:
src/__init__.py	94%	:white_check_mark:
src/api/__init__.py	85%	:white_check_mark:
src/api/auth.py	43%	:x:
src/api/club_events.py	66%	:x:
src/api/email_verification.py	35%	:x:
src/api/hackers.py	56%	:x:
src/common/decorators.py	87%	:white_check_mark:
src/common/init_defaults.py	56%	:x:
src/common/json.py	77%	:white_check_mark:
src/common/jwt.py	73%	:x:
src/common/mail.py	52%	:x:
src/models/hacker.py	94%	:white_check_mark:
src/models/sponsor.py	64%	:x:
src/models/user.py	88%	:white_check_mark:
src/tasks/__init__.py	78%	:white_check_mark:
src/tasks/clubevent_tasks.py	19%	:x:
src/tasks/mail_tasks.py	45%	:x:

Minimum allowed coverage is 75%

Generated by :monkey: cobertura-action against 7a731036c74416a6168667f3fd08d1ea841c8060

[TorrentofShame]

The current CORS policy of the backend does not restrict what origin to accept request from.

As such, any issue with CORS must be resolved on the frontend.