Update airflow to version 2.6.1

A new version of Airflow has been released by upstream and we wish to incorporate this into our Conda environment for Airflow.

This commit updates the conda-environment.yml file with the new version number and includes associated updates in the generated conda-environment.lock.yaml

The version number of the package has also been updated to reflect the version of airflow contained, as well as the date of the build.

Bug: T336286