Change project settings

[srgoogle23]

This pull request includes several changes to improve the configuration and setup of the project, including updates to environment variables, Docker configurations, and workflows. The most important changes are grouped into environment configuration updates, Docker-related changes, and workflow improvements.

Environment Configuration Updates:

• Updated database credentials in .env.example to use the encurtador database, username, and password.

Docker-related Changes:

• Removed the default Dockerfile in .github/workflows/Dockerfile.
• Updated the Dockerfile to use hyperf:8.3-alpine-v3.20-swoole, set the timezone to America/Sao_Paulo, and added copying of .env.example to the working directory. [1] [2]
• Modified docker-compose.yml to update the entrypoint for the encurtador service to include Composer installation and migration commands.

Workflow Improvements:

• Added a new GitHub Actions workflow in test.yml to run tests with Composer, including steps for setting up Docker and Docker Compose, running tests, and shutting down containers.

Documentation Changes:

• Removed the introductory and installation sections from README.md to simplify the documentation.