feat: add flask cors to allow running multiple servers locally

[mtreacy002]

Description

Added cors to allow requests from frontend (cross origin) for testing BIT functionality like register user PR#18

Fixes #51

How Has This Been Tested?

Register new user from BIT React UI while running BIT and MS backend servers.

Checklist:

• My PR follows the style guidelines of this project
• I have performed a self-review of my own code or materials

Code/Quality Assurance Only

• My changes generate no new warnings
• [x]existing unit tests pass locally with my changes

Additional note

• new dependencies added inside requirements.txt so need to reinstall dependencies by running pip install -r requirements.txt

[mtreacy002]

@anitab-org/bridgeintech-maintainers . We need to have this approve for mentors to be able to test Register UI since they need to run BIT and MS backend locally.

[meenakshi-dhanani]

So I started my frontend and made a register request to the backend. I was able to do so successfully. So the PR seems fine :) Approving

[foongminwong]

Able to install the flask-cors dependency locally and test the register ui functionality successfully