Add Pytests - Will become the main testing framework

[codecov[bot]]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (6a20760) 87.89% compared to head (16aa396) 87.90%.

Files	Patch %	Lines
api/validators.py	92.30%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## development #200 +/- ## ============================================ Coverage 87.89% 87.90% ============================================ Files 59 59 Lines 4471 4481 +10 ============================================ + Hits 3930 3939 +9 - Misses 541 542 +1 ``` | [Flag](https://app.codecov.io/gh/Major-League-Summer-Baseball/mlsb-platform/pull/200/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Major-League-Summer-Baseball) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/Major-League-Summer-Baseball/mlsb-platform/pull/200/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Major-League-Summer-Baseball) | `87.90% <94.11%> (+<0.01%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Major-League-Summer-Baseball#carryforward-flags-in-the-pull-request-comment) to find out more.

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