DevOps: Add pr_checks_backend

[zackdreitzler]

Describe the task

Add the pr_checks_backend.yml file as a GitHub Actions workflow. The goal of this is to show every developer/reviewer that a PR impacting the data folder can successfully build and run the vacant-lots-proj. This also sets a foundational workflow that can be used to run a data quality check, formatter, and/or linter checks.

Acceptance Criteria

• [ ] The workflow should only trigger when changes are found in the data directory or any of the subdirectories
• [ ] The workflow should contain a docker-compose run vacant-lots-proj step
  • [ ] On success this step reports success to the PR that triggered this action
  • [ ] On failure this step reports a failure to the PR that triggered this action

Additional context

This is currently blocked by #630. The postgres DB is required to get the docker build and run to be successful.