**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
"""Update edges_to_add and edges_to_skip according to TaskGroups."""
        if isinstance(task_group, BaseOperator):
            return
        for target_id in task_group.downstream_group_ids:
            
            
            target_group = task_group_map[target_id]
            edges_to_add.add((task_group.downstream_join_id, target_group.upstream_join_id))
            for child in task_group.get_leaves():
                edges_to_add.add((child.task_id, task_group.downstream_join_id))
                for target in target_group.get_roots():
                    edges_to_skip.add((child.task_id, target.task_id))
                edges_to_skip.add((child.task_id, target_group.upstream_join_id))
            for child in target_group.get_roots():
                edges_to_add.add((target_group.upstream_join_id, child.task_id))
                edges_to_skip.add((task_group.downstream_join_id, child.task_id))
        
        
        
        for target_id in task_group.downstream_task_ids:
            edges_to_add.add((task_group.downstream_join_id, target_id))
            for child in task_group.get_leaves():
                edges_to_add.add((child.task_id, task_group.downstream_join_id))
                edges_to_skip.add((child.task_id, target_id))