**Apache Airflow version**: 2.1.0

**Browsers**: Chrome and Firefox

**What happened**:

Before upgrading to 2.1.0

![before](https://user-images.githubusercontent.com/14293802/120359517-c1ca1100-c2d5-11eb-95ba-58ccc0a3ac37.png)

After upgrading to 2.1.0

![after](https://user-images.githubusercontent.com/14293802/120359528-c4c50180-c2d5-11eb-8e04-f34846ea2736.png)

**What you expected to happen**:

Show/Edit/Delete under Security -> Users are available

<!-- What do you think went wrong? -->

**How to reproduce it**:

Go to Security -> Users (as an admin of course) 
airflow/www/views.py
attr = getattr(ti, attr_name)
                if type(attr) != type(self.task):  
                    ti_attrs.append((attr_name, str(attr)))
        task_attrs = []
        for attr_name in dir(task):
            if not attr_name.startswith('_'):
                attr = getattr(task, attr_name)
                if type(attr) != type(self.task) and attr_name not in wwwutils.get_attr_renderer():  
                    task_attrs.append((attr_name, str(attr)))
        
        special_attrs_rendered = {}
        for attr_name in wwwutils.get_attr_renderer():
            if getattr(task, attr_name, None) is not None:
                source = getattr(task, attr_name)
                special_attrs_rendered[attr_name] = wwwutils.get_attr_renderer()[attr_name](source)
        no_failed_deps_result = [
            (
                "Unknown",
                "All dependencies are met but the task instance is not running. In most "
                "cases this just means that the task will probably be scheduled soon "
                "unless:<br>\n- The scheduler is down or under heavy load<br>\n{}\n"
                "<br>\nIf this task instance does not start soon please contact your "
                "Airflow administrator for assistance.".format(
                    "- This task instance already ran and had it's state changed manually "
                    "(e.g. cleared in the UI)<br>"
                    if ti.state == State.NONE
                    else ""
                ),
            )
        ]