Add episode group endpoint

[Joost1991]

Could you add the episode group endpoint?

https://developers.themoviedb.org/3/tv-episode-groups/get-tv-episode-group-details

I tried something in the tv.py, but not sure if it meets the requirements.

_urls = {
        "details": "/tv/%s",
        "episode_group": "/tv/episode_group/%s",
        "latest": "/tv/latest",
        "search_tv": "/search/tv",
        "popular": "/tv/popular",
        "top_rated": "/tv/top_rated",
        "similar": "/tv/%s/similar",
        "recommendations": "/tv/%s/recommendations",
        "videos": "/tv/%s/videos",
        "airing_today": "/tv/airing_today",
        "on_the_air": "/tv/on_the_air",
        "screened_theatrically": "/tv/%s/screened_theatrically",
        "external_ids": "/tv/%s/external_ids",
        "reviews": "/tv/%s/reviews",
        "keywords": "/tv/%s/keywords",
    }

def episode_group(
            self, episode_group_id
    ):
        """
        Get a specific TV episode group by id.
        :param episode_group_id:
        :return:
        """
        return AsObj(
            **self._call(
                self._urls["episode_group"] % str(episode_group_id),
                ""
                )
        )```