### Discussed in https://github.com/apache/airflow/discussions/33345

<div type='discussions-op-text'>

<sup>Originally posted by **vuphamcs** August 11, 2023</sup>
### Description

Is there a variable similar to `prev_start_date_success` but for the previous DAG run’s completion date? The value I’m hoping to retrieve to use within the next DAG run is `2023-08-10 16:04:30`

![image](https://github.com/apache/airflow/assets/1600760/9e2af349-4c3e-47e1-8a1a-9d8827b56f57)


### Use case/motivation

One particular use case is to help guarantee that the next DAG run only queries data that was inserted during the existing DAG run, and not the past DAG run.

```python
prev_ts = context['prev_end_date_success']

sql = f"SELECT * FROM results WHERE created_at > {context['prev_end_date_success']}"
```

### Related issues

_No response_

### Are you willing to submit a PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)
</div>
try:
            result = subprocess.check_output([self.python, "--version"], text=True)
            return result.strip().split(" ")[-1].split(".")
        except Exception as e:
            raise ValueError(f"Error while executing {self.python}: {e}")
    def _iter_serializable_context_keys(self):
        yield from self.BASE_SERIALIZABLE_CONTEXT_KEYS
        if self._get_airflow_version_from_target_env():
            yield from self.AIRFLOW_SERIALIZABLE_CONTEXT_KEYS
            yield from self.PENDULUM_SERIALIZABLE_CONTEXT_KEYS
        elif self._is_pendulum_installed_in_target_env():
            yield from self.PENDULUM_SERIALIZABLE_CONTEXT_KEYS
    def _is_pendulum_installed_in_target_env(self) -> bool:
        try:
            subprocess.check_call([self.python, "-c", "import pendulum"])
            return True
        except Exception as e:
            if self.expect_pendulum:
                self.log.warning("When checking for Pendulum installed in virtual environment got %s", e)
                self.log.warning(
                    "Pendulum is not properly installed in the virtual environment "
                    "Pendulum context keys will not be available. "
                    "Please Install Pendulum or Airflow in your virtual environment to access them."
                )
            return False
    def _get_airflow_version_from_target_env(self) -> str | None: