**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
match = re.search(r"_copy(\d+)$", selected_conn.conn_id)
            if match:
                conn_id_prefix = selected_conn.conn_id[: match.start()]
                new_conn_id = f"{conn_id_prefix}_copy{int(match.group(1)) + 1}"
            else:
                new_conn_id += '_copy1'
            dup_conn = Connection(
                new_conn_id,
                selected_conn.conn_type,
                selected_conn.description,
                selected_conn.host,
                selected_conn.login,
                selected_conn.password,
                selected_conn.schema,
                selected_conn.port,
                selected_conn.extra,
            )
            try:
                session.add(dup_conn)
                session.commit()
                flash(f"Connection {new_conn_id} added successfully.", "success")
            except IntegrityError:
                flash(
                    f"Connection {new_conn_id} can't be added. Integrity error, probably unique constraint.",
                    "warning",
                )
                session.rollback()
        self.update_redirect()
        return redirect(self.get_redirect())
    def process_form(self, form, is_created):