Use dependency-group for "dev" and other non-user-facing dependencies

pyproject.toml specifies two types of dependency sets: "extras" and "groups." The first is specified by [project.optional-dependencies] (this is what we have now), and the second is specified by [dependency-groups]. Extras may be installed with the package-name[extra-name] syntax, while groups are not supposed to be user-facing, are not listed on PyPI, and may be installed with the --group flag.

I propose making "dev" a dependency group in the template and changing CI/setup scripts to use it this way. This will make the extras list cleaner.

https://packaging.python.org/en/latest/specifications/pyproject-toml/#dependencies-optional-dependencies
https://packaging.python.org/en/latest/specifications/dependency-groups/

LSDB at PyPI

首先檢查範本的 pyproject.toml，以及用於安裝開發相依項目的 CI 和設定指令碼。更新範本，使開發相依項目和其他非面向使用者的相依項目使用 [dependency-groups]，並確保這些指令碼使用群組機制；當 extras 清單不再包含開發相依項目，且產生專案的設定仍能正常運作時，即表示完成。