**Apache Airflow version**: 2.1.1

**What happened**:

The rendered templates screen doesn't show the operator arguments for TaskFlow API operators.
![image](https://user-images.githubusercontent.com/72943478/125486179-f6dde0be-9f60-4aca-831a-5cfd16e7f006.png)

**What you expected to happen**:

Should show the arguments after any templates have been rendered.

**How to reproduce it**:

Will happen for any `@task` decorated operator.

**Anything else we need to know**:

This issue appears on a number of operators.  Possible solution is to modify the "get_python_source" in utils/code_utils.py to handle list and dict. This would cause any operator that using py as the renderer to handle lists and dicts.  Possibly something like:
```
    if isinstance(x, list):
        return [str(v) for v in x]

    if isinstance(x, dict):
        return {k: str(v) for k, v in x.items()}
```
The converting values to strings seems necessary in order to avoid errors when this is passed to the pygments lexer.
![image](https://user-images.githubusercontent.com/72943478/125494716-01cf0c11-9e5f-45fa-afe2-4f99409edefc.png)

airflow/www/views.py
"""Set state to 'up_for_retry'"""
        self.set_task_instance_state(tis, State.UP_FOR_RETRY)
        self.update_redirect()
        return redirect(self.get_redirect())
class DagModelView(AirflowModelView):
    """View to show records from DAG table"""
    route_base = '/dagmodel'
    datamodel = AirflowModelView.CustomSQLAInterface(DagModel)  
    class_permission_name = permissions.RESOURCE_DAG
    method_permission_name = {
        'list': 'read',
        'show': 'read',
    }
    base_permissions = [
        permissions.ACTION_CAN_READ,
        permissions.ACTION_CAN_EDIT,
        permissions.ACTION_CAN_DELETE,
    ]
    list_columns = [
        'dag_id',
        'is_paused',
        'last_parsed_time',
        'last_expired',
        'scheduler_lock',
        'fileloc',
        'owners',
    ]
    formatters_columns = {'dag_id': wwwutils.dag_link}
    base_filters = [['dag_id', DagFilter, lambda: []]]
    def get_query(self):