
**Apache Airflow version**:

master

**What happened**:

https://github.com/apache/airflow/blob/master/airflow/models/baseoperator.py#L356 --> should be timedelta not datetime


airflow/models/baseoperator.py
self,
        content: Any,
        context: Dict,
        jinja_env: Optional[jinja2.Environment] = None,
        seen_oids: Optional[Set] = None,
    ) -> Any:
        """
        Render a templated string. The content can be a collection holding multiple templated strings and will
        be templated recursively.
        :param content: Content to template. Only strings can be templated (may be inside collection).
        :type content: Any
        :param context: Dict with values to apply on templated content
        :type context: dict
        :param jinja_env: Jinja environment. Can be provided to avoid re-creating Jinja environments during
            recursion.
        :type jinja_env: jinja2.Environment
        :param seen_oids: template fields already rendered (to avoid RecursionError on circular dependencies)
        :type seen_oids: set
        :return: Templated content
        """
        if not jinja_env:
            jinja_env = self.get_template_env()