**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
for source_id in task_group.upstream_task_ids:
            edges_to_add.add((source_id, task_group.upstream_join_id))
            for child in task_group.get_roots():
                edges_to_add.add((task_group.upstream_join_id, child.task_id))
                edges_to_skip.add((source_id, child.task_id))
        for child in task_group.children.values():
            collect_edges(child)
    collect_edges(dag.task_group)
    
    edges = set()
    def get_downstream(task):
        for child in task.downstream_list:
            edge = (task.task_id, child.task_id)
            if edge not in edges:
                edges.add(edge)
                get_downstream(child)
    for root in dag.roots:
        get_downstream(root)
    result = []
    
    
    for source_id, target_id in sorted(edges.union(edges_to_add) - edges_to_skip):
        record = {"source_id": source_id, "target_id": target_id}
        label = dag.get_edge_info(source_id, target_id).get("label")
        if label:
            record["label"] = label
        result.append(record)
    return result
def circles(error):