Pyproject2conda

Changed

- Bugfix in pre-commit hooks. Now respects `header = false` in environments.

Added

- Added pre-commit hooks `pyproject2conda-project`, `pyproject2conda-yaml`, and
`pyproject2conda-requirements`.

Changed

- Changed default of `--overwrite` to `force`. This simplifies using with
`pre-commit`.
- `--commit-command` defaults to `pre-commit` when run under pre-commit

Added

- Can now specify current package in dependency-groups like with extras. For
example, with:

toml
[project]
name = "mypackage"
...

optional-dependencies.opt = [ "opt1" ]

[dependency-groups]
dev = [
"pytest",
"mypackage[opt]"
]


Will render optional dependencies from `opt` extra when using group `dev`

- Added flag `--pip-only` to treat all requirements as pip requirements in
`environment.yaml` files. Closes 8

Changed

- Read default version from first found file, in order,
`.python-version-default` and `.python-version`. This allows for "default"
version being different from pinned version specifier, as the latter can be a
range of python values.

Added

- Can now pass requirements for package with `--req/-r "-e ."` for example.

Added

- `--python` flag now accepts options `default`, `all`, `lowest`, and `highest`.
`default` sets python to value found in `.python-version` file in current
directory. Other options extract values entries of form
`"Programming Language :: Python :: 3.10"'`, etc,from
`pyproject.toml:project.classifiers` table.

- `all`: All specified python version
- `lowest`: Lowest python version
- `highest`: Highest python version

- Added `--reqs-ext` and `--yaml-ext` options.