Fix hyphens in path parameters

[harabat]

Fixes #976 and #578, and replaces #978.

@dbanty please choose your preferred approach between this and PR #987.

The original issue is that openapi-python-client throws incorrect path templating warnings when the path has a parameter with a hyphen and consequently fails to generate the endpoints.

---

The first commit ensures that hyphens are recognised as allowed delimiters in parameter path names. This allows the endpoints to be generated.

However, this generates lines like these:

def _get_kwargs(
    user_id: int,
) -> Dict[str, Any]:
    _kwargs: Dict[str, Any] = {
        "method": "post",
        "url": "/activitypub/user-id/{user-id}/inbox".format(user-id=user_id,),
    }
    return _kwargs

Since Python variable names cannot contain hyphens, the user-id parameter name here will trigger errors (starting with ruff).

---

The second commit replaces parameter names with their python_name in __init__.py and passes the modified path to templates/endpoint_module.py.jinja.

This fixes the issue and allows endpoints to be generated correctly.

---

#987 is a different option for the second commit which instead creates a custom Jinja filter in utils.py and so that the parameter names in endpoint.path can be converted to their python names directly in templates/endpoint_module.py.jinja.

Both approaches are equivalent and have been tested with different parameter names (snake case, camel case, kebab case, mixed).

[dbanty]

Wow, not just a fix for the bug, but 2 choices! Thanks a bunch ☺️

[harabat]

Thanks @dbanty!