The 'funcsigs==1.0.0' distribution was not found and is required by apache-airflow

When installing apache-beam [gcp]==2.16.0 with airflow this error is triggered:

pkg_resources.DistributionNotFound: The 'funcsigs==1.0.0' distribution was not found and is required by apache-airflow

It seems to be a dependency conflict with Beam 2.16. There should be an update of the version of 'funcsigs' in Airflow [1] to match that of the latest Beam 2.16 [2] in order to resolve this conflict.

The workaround is to use  apache-beam [gcp]==2.15.0 or less.

[1] https://github.com/apache/airflow/blob/v1-10-stable/setup.py#L363
[2] https://github.com/apache/beam/blob/master/sdks/python/setup.py#L113