Hotfix to enable latest version of azureml-dataprep

What's Changed

AzureML has deployed code that is not compatible with versions of azureml-dataprep before 5.1.6. However, that version 5.1.6 does not have the MountContext class that hi-ml-azure is using.

hi-ml-azure

• ENH: Remove mount context imports by @ant0nsc in #919

Full Changelog: v0.4.1...v0.4.2