Develop tests to interface with test database

[maxachis]

Context

Based originally off of #71. Per https://github.com/Police-Data-Accessibility-Project/data-sources-app/issues/271, we've now set up a Development/Testing database that pulls daily from the production database. Now we need to create more tests for it.

Requirements

• Develop tests of various functionality that interfaces with the development database to confirm their intended functionality.
• Create Github Action which can run these tests regularly on pull requests
• Update readme for instructions on what is required to run these tests (should be similar to before, but will require Dev connection string).

Tests

• You bet!

Docs

• Updated readme, as mentioned above.

Open questions

• @josh-chamberlain has discussed how we probably want a lot of our database interactions to occur via the API. This issue may be implicated in that.

[josh-chamberlain]

@maxachis do you want help figuring out which things to test?

[maxachis]

@maxachis do you want help figuring out which things to test?

@josh-chamberlain I'll always accept help! What would help most prominently, at least for issue definition, is a high-level overview of what modules/functions/cases to test.