pyproject.toml:
Include the tests using poetry's integration for includes instead of
packages, as the latter leads to the tests being added to packages in
the generated setup.py.

Fixes #11

pyproject.toml:
Add pytest configuration to setup the custom marker "integration".

pyproject.toml:
Add subprocess-tee to the list of dependencies for the project.

pyproject.toml:
Add script entrypoint for `json2db`.

pyproject.toml:
Add jinja2 as repository dependency.

pyproject.toml:
Add a script setup for dbj2son pointing to `repo_management.cli:db2json`.
This can be used via `poetry run db2json`.

pyproject.toml:
Add orjson to the list of dependencies.
Add mock to the list of development dependencies.

pyproject.toml:
Add pydantic to dependencies, as it will be used to validate
configuration and internal typing.

pyproject.toml:
Add a pyproject.toml for describing the project, configuring all
currently required dependencies and development dependencies.
The configuration adds entries for the code formatter black, the import
sorting tool isort and for the coverage report generation tool coverage.