fix(gitlab): resolve new Python typings issues and warnings

# Standard libraries

from time import sleep

from typing import cast, Dict, List, Optional, Union

from typing import Dict, List, Optional, Union

# Modules libraries

from gitlab import Gitlab

from gitlab.base import RESTObject, RESTObjectList

from gitlab.const import AccessLevel as GitLabAccessLevel

from gitlab.exceptions import (

    GitlabDeleteError,

    def group_get_labels(

        self,

        criteria: str,

    ) -> Union[RESTObjectList, List[RESTObject]]:

    ) -> List[GroupLabel]:

        # Get group labels

        group = self.group(criteria)

    def project_get_issues_boards(

        self,

        criteria: str,

    ) -> Union[RESTObjectList, List[RESTObject]]:

    ) -> List[ProjectBoard]:

        # Get project issues boards

        project = self.project(criteria)

    def project_get_labels(

        self,

        criteria: str,

    ) -> Union[RESTObjectList, List[RESTObject]]:

    ) -> List[ProjectLabel]:

        # Get project labels

        project = self.project(criteria)

    ) -> User:

        users = self.__gitlab.users.list(all=True, iterator=True, username=criteria)

        for user in users:

            return cast(User, user)

            return user

        raise RuntimeError(f'Could not find user {criteria}')

    # User name