Pydantic >2 compability and package modernization

[GPla]

Hi there,

With this pull request, I added support for pydantic>2 by utilizing the pydantic.v1 import (as mentioned in #56).
Thereby, any version of pydantic >1.5 will work with this package and one could gradually update the internals to use the new pydantic v2 API.

Furthermore, I did some package modernization:

• Switch to using pyproject.toml for all configuration purposes
• Github actions with matrix to test all supported python versions (3.7-3.12)
• Linting + type checking hooks via pre-commit
• Change linter from black to ruff (similar output to black but much faster)
• Support for rye during development

see here for tests

[GPla]

Open TODOs would:

• remove .circle-ci if github actions are okay
• add disclaimer in readme that v1 API is used via pydantic.v1 under pydantic>2