fix: Team add member

[FranzForstmayr]

Description

This PR adds an unit test to the teams/<id>/members/add and .../remove endpoints, which are not working currently.

The endpoints were missing the users_service dependency, which was added.
In TeamService just the tag_name is passed to slugify, as this function accepts only strings.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[FranzForstmayr]

I get one more warning while running the unit tests now, but I'm not sure how to fix this:

tests/integration/test_teams.py::test_teams_add_remove_member
  sys:1: SAWarning: Object of type <Team> not in session, add operation along 'Tag.teams' won't proceed (This warning originated from the Session 'autoflush' process, which was invoked automatically in response to a user-initiated operation. Consider using ``no_autoflush`` context manager if this warning happended while initializing objects.)

[cofin]

I get one more warning while running the unit tests now, but I'm not sure how to fix this:

tests/integration/test_teams.py::test_teams_add_remove_member
  sys:1: SAWarning: Object of type <Team> not in session, add operation along 'Tag.teams' won't proceed (This warning originated from the Session 'autoflush' process, which was invoked automatically in response to a user-initiated operation. Consider using ``no_autoflush`` context manager if this warning happended while initializing objects.)

We need to specify this as having an eager load. I'll take a look today. Thanks for the PR