Airflow 2.1.0, Docker

**What happened**:

Users with the Guest role assigned are stuck in a redirect loop once they attempt to login successfully to the web interface.

**What you expected to happen**:

Get minimal access to the dashboard with the appropriate views for a guest role

**How to reproduce it**:
1. Assign a guest role to any user and remove any other roles with the administrator user.
2. Logout from the admin account 
3. Login as the guest user
4. You will notice constant HTTP redirects, and the dashboard will not show up.


airflow/www/views.py
"""
    Cast the task_duration to an int was for optimization for large/huge dags if task_duration > 10s
    otherwise we keep it as a float with 3dp
    """
    return int(task_duration) if task_duration > 10.0 else round(task_duration, 3)
def get_safe_url(url):
    """Given a user-supplied URL, ensure it points to our web server"""
    valid_schemes = ['http', 'https', '']
    valid_netlocs = [request.host, '']
    if not url:
        return url_for('Airflow.index')
    parsed = urlparse(url)
    
    
    if ';' in unquote(url):
        return url_for('Airflow.index')
    query = parse_qsl(parsed.query, keep_blank_values=True)
    url = parsed._replace(query=urlencode(query)).geturl()
    if parsed.scheme in valid_schemes and parsed.netloc in valid_netlocs:
        return url
    return url_for('Airflow.index')
def get_date_time_num_runs_dag_runs_form_data(www_request, session, dag):