Need the ability to automate continuous integration checks

[sylviewn]

As a Developer
I need automation to build and test every pull request
So thatI do not have to rely on manual testing of each request, which is time-consuming

Assumptions
* GitHub Actions will be used for the automation workflow
* The workflow must include code linting and testing
* The Docker image should be postgres:alpine for the database
* A GitHub Actions badge should be added to the README.md to reflect the build status

Acceptance Criteria

Given code is ready to be merged
When a pull request is created
Then GitHub Actions should run linting and unit tests
And the badge should show that the build is passing