Fixing Test Errors and Updating Test Cases

Fixes #64

Description / Changes Made

I first modified all current test cases by pointing them to the proper imports.
I then modified the test cases in order from top-down:
- test_create_delete_user.py & test_get_update_user.py : ChatGPT Reference
- For the above files I used the ChatGPT reference to help recreate the test case and properly validate the create_user() and delete_user() routes. I found that we can mimic calls to the Firebase database using the unittest.mock patch import. This allows us to avoid interacting with the database itself to test routes which is a part of issue #64
- After finishing the create and delete routes I refactored the get and update routes into the file above but changed the name to test_users.py. This simplifies 2 test cases into one and reduces the need for the same code for start-up in 2 different files.
- test_post_validation : [ChatGPT Reference]()
- test_posts : [ChatGPT Reference]()

![IMPORT PICTURE OF COVERAGE REPORT AT THE END HERE]()

_Run the runtests.py test suite in the backend folder to run all test scripts and display a coverage report.

[ ] I have added/updated relevant documentation, and I have followed the coding style guidelines.
[ ] I have added/updated tests, and I have run the test suite and all tests pass.
[ ] I have checked for any potential conflicts with other branches and fixed any merge conflicts.