devops: Test Gitverse CI/CD, #4.

devops: Test Gitverse CI/CD, #3.

devops: Test Gitverse CI/CD, #2.

devops: Test Gitverse CI/CD.

lint: Add mypy to project, fix 4 errors.

docker: Added Docker Compose configuration.

tests: Added tests for 100% coverage.

tests: Added DB tests with FactoryBoy-generated data.

tests: Tests for service.client_parkings complete.

tests: Add tests for client_parkings.park_client().

refactor: Return plain dicts from data.client_parkings functions.

tests: Add isolated tests for service.parkings.

refactor: Return plain dicts from data.parkings functions.

refactor: Rename get_parking() to get_parking_json().

refactor: Optimise imports for testing.

tests: Add isolated tests for service.clients.

tests: Configure isolated test for service.clients.

tests: Add tests for app.client_parkings.

tests: Add tests for parkings.

tests: Add pytest-cov to project.

tests: Add tests for app.clients.