update person

[Taniya-Das]

Change

Updates Person.
Refer to Issue #494
Will add the Alembic migration script once this PR is approved.

How to Test

Test using unit test and spinning docker containers.

Checklist

• [x ] Tests have been added or updated to reflect the changes, or their absence is explicitly explained.
• [ x] Documentation has been added or updated to reflect the changes, or their absence is explicitly explained.
• [x ] A self-review has been conducted checking:
  • No unintended changes have been committed.
  • The changes in isolation seem reasonable.
  • Anything that may be odd or unintuitive is provided with a GitHub comment explaining it (but consider if this should not be a code comment or in the documentation instead).
• [ x] All CI checks pass before pinging a reviewer, or provide an explanation if they do not.

Related Issues

[Taniya-Das]

Does it make more sense to define member and member_of field in Agent class instead of Organisation and Person respectively.