
**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: jinja2.Environment, seen_oids: Set
    ) -> None:
        if id(content) not in seen_oids:
            seen_oids.add(id(content))
            try:
                nested_template_fields = content.template_fields
            except AttributeError:
                
                return
            self._do_render_template_fields(content, nested_template_fields, context, jinja_env, seen_oids)
    def get_template_env(self) -> jinja2.Environment:
        """Fetch a Jinja template environment from the DAG or instantiate empty environment if no DAG."""
        return self.dag.get_template_env() if self.has_dag() else jinja2.Environment(cache_size=0)  
    def prepare_template(self) -> None:
        """
        Hook that is triggered after the templated fields get replaced
        by their content. If you need your operator to alter the
        content of the file before the template is rendered,
        it should override this method to do so.
        """
    def resolve_template_files(self) -> None: