**Description**

Files are not part of the templated fields in the `EmailOperator` https://airflow.apache.org/docs/stable/_modules/airflow/operators/email_operator.html

Whle in fact file names should also be templated .

**Use case / motivation**
We want to store files accordingly to the DAGs execution date and further send them to email recipients like so:

```
send_report_email = EmailOperator(
        ....
        files=[
            "/tmp/Report-A-{{ execution_date.strftime('%Y-%m-%d') }}.csv",
            "/tmp/Reportt-B-{{ execution_date.strftime('%Y-%m-%d') }}.csv"
        ]
```

airflow/operators/email.py
#
#
#
from typing import List, Optional, Union
from airflow.models import BaseOperator
from airflow.utils.decorators import apply_defaults
from airflow.utils.email import send_email
class EmailOperator(BaseOperator):