Import issues when using older Airflow version (1.10.5)

[JunqiYangjqy]

Hi Hightouch :),

Seems like in Airflow 1.10.5 the BaseOperatorLink is inside the BaseOperator.py
Therefore it caused failure when importing Hightouch.

The error message resembles:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.6/dist-packages/airflow_provider_hightouch/operators/hightouch.py", line 4, in <module>
    from airflow.models import BaseOperator, BaseOperatorLink
ImportError: cannot import name 'BaseOperatorLink'

I just checked Airflow 1.10.5:

Is that possible to have a fix on this please?
Many thanks :)