## Is your feature request related to a problem?

You can currently install plugins from Github and NPM sources, but not GitLab

## Describe the solution you'd like

Copy a GitLab URL to install a plugin

## Describe alternatives you've considered

Using the plugin source editor.

## Additional context

Came from a conversation in the Users' slack

#### *Thank you* for your feature request – we love each and every one!

posthog/plugins/utils.py
parsed_url = parse_url(url)
    if parsed_url["type"] == "github":
        if not (tag or parsed_url.get("tag", None)):
            raise Exception("No Github tag given!")
        url = "https://github.com/{user}/{repo}/archive/{tag}.zip".format(
            user=parsed_url["user"], repo=parsed_url["repo"], tag=tag or parsed_url["tag"]
        )
    elif parsed_url["type"] == "npm":
        if not (tag or parsed_url.get("version", None)):
            raise Exception("No NPM version given")
        url = "https://registry.npmjs.org/{pkg}/-/{pkg}-{version}.tgz".format(
            pkg=parsed_url["pkg"], version=tag or parsed_url["version"]
        )
    else:
        raise Exception("Unknown Repository Format")
    response = requests.get(url)
    if not response.ok:
        raise Exception("Could not download archive from {}".format(parsed_url["type"]))
    return response.content
def load_json_file(filename: str):
    try:
        with open(filename, "r") as reader:
            return json.loads(reader.read())
    except FileNotFoundError:
        return None
def get_json_from_zip_archive(archive: bytes, filename: str):