postman integration

[jmensch1]

Fixes #684

This integrates Postman tests into our backend CI workflow, so we can make sure all the endpoints are working before a pull request is accepted to dev or master. Here's how it works:

• install the backend on the CI ubuntu instance using docker-compose
• populate the db with 500 rows, and run the api
• run a separate docker container that hits the api with all of the tests in the Postman CI collection
• stop the build if any of the tests fails

The CI collection includes 15 api calls to test the endpoints. They include both good input and bad input (like missing required params, nonexistent endpoints). The results are reported in on the Actions tab:

The CI tests can also be run locally in Postman itself (the GUI version), and there's a README explaining how to import and run them.

Other things in the PR: (1) a couple of new unit tests (using pytest), (2) added sendgrid to the backend dependencies, which I forgot to do in my last PR.

• Up to date with dev branch
• Branch name follows guidelines
• All PR Status checks are successful
• Peer reviewed and approved

Any questions? See the getting started guide

[adamkendis]

Good stuff, I never thought of using Postman in CI. Awesome.