Refactor Alembic configuration and update Docker setup

- Removed the `alembic.ini` file and migrated its configuration to `pyproject.toml` under `[tool.alembic]`, enhancing project organization.
- Updated the `Dockerfile` to copy `pyproject.toml` instead of `alembic.ini`, ensuring the new configuration is utilized during the build process.
- Modified `entrypoint.sh` to use the new Alembic configuration from `pyproject.toml` for database migrations.
- Updated README documentation to reflect the new Alembic configuration and usage instructions.

pyproject.toml

@@ -33,6 +33,11 @@ dev = [
 where = ["."]
 include = ["duty_teller*"]
 
+[tool.alembic]
+script_location = "alembic"
+prepend_sys_path = "."
+version_path_separator = "os"
+
 [tool.black]
 line-length = 120
 target-version = ["py311"]