**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
'log_url',
    ]
    order_columns = [
        item for item in list_columns if item not in ['try_number', 'log_url', 'external_executor_id']
    ]
    search_columns = [
        'state',
        'dag_id',
        'task_id',
        'execution_date',
        'hostname',
        'queue',
        'pool',
        'operator',
        'start_date',
        'end_date',
        'queued_dttm',
    ]
    edit_columns = [
        'state',
        'dag_id',
        'task_id',
        'execution_date',
        'start_date',
        'end_date',
    ]
    edit_form = TaskInstanceEditForm
    base_order = ('job_id', 'asc')
    base_filters = [['dag_id', DagFilter, lambda: []]]
    def log_url_formatter(self):