Add testing to continous integration (CI)

### Dependency
- [ ] A working version of PeopleDepot - see [comment below](https://github.com/hackforla/peopledepot/issues/344#issuecomment-2207408717)

### Overview

We need to run pytest in continuous integration (CI) so that we know PRs aren't broken.

### Action Items

- [ ] Add a GitHub Action (GHA) workflow to check out the code and run tests
- [ ] Add a step to call the check migration management command from #348
- [ ] Remove test step from pre-commit config

### Resources/Instructions

Maybe something like this
- but this doesn't actually run the tests that it's supposed to. It needs debugging.
```yml
name: Run all tests

on:
push:
branches: [ main ]
pull_request:
branches: [ main ]
workflow_dispatch:

jobs:
test:
runs-on: ubuntu-latest

steps:
- name: Check out project
uses: actions/checkout@v3

- name: Set up Python
uses: actions/setup-python@v3
with:
python-version: '3.x'

- name: Install dependencies
run: cd app/ || pip3 install -r requirements.txt

- name: Execute tests
run: cd app/ || python3 -m pytest -v
```