### Apache Airflow version

2.2.0b2 (beta snapshot)

### Operating System

Debian buster

### Versions of Apache Airflow Providers

_No response_

### Deployment

Astronomer

### Deployment details

Astro dev start

### What happened

Unable to change username while updating user information through API though it's possible from UI.

### What you expected to happen

Either username should not be editable from UI or It should be editable from API.

### How to reproduce

1. Use a patch request with the below URL.
`{{url}}/users/{{username}}`
2. In payload use a different username
```
 {
        "username": "{{username1}}",
        "password": "password1",
        "email": "{{email}}@example.com",
        "first_name": "{{$randomFirstName}}",
        "last_name": "{{$randomLastName}}",
        "roles":[{ "name": "Op"}]
}
```


### Anything else

_No response_

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

tests/api_connexion/endpoints/test_user_endpoint.py
users = self._create_users(200)
        self.session.add_all(users)
        self.session.commit()
        response = self.client.get("/api/v1/users?limit=180", environ_overrides={'REMOTE_USER': "test"})
        assert response.status_code == 200
        assert len(response.json['users']) == 150
EXAMPLE_USER_NAME = "example_user"
EXAMPLE_USER_EMAIL = "example_user@example.com"
def _delete_user(**filters):
    with create_session() as session:
        user = session.query(User).filter_by(**filters).first()
        if user is None:
            return
        user.roles = []
        session.delete(user)
@pytest.fixture()
def autoclean_username():
    _delete_user(username=EXAMPLE_USER_NAME)
    yield EXAMPLE_USER_NAME
    _delete_user(username=EXAMPLE_USER_NAME)
@pytest.fixture()
def autoclean_email():
    _delete_user(email=EXAMPLE_USER_EMAIL)
    yield EXAMPLE_USER_EMAIL
    _delete_user(email=EXAMPLE_USER_EMAIL)
@pytest.fixture()
def user_with_same_username(configured_app, autoclean_username):