Update to allow core/3.100.

[ggainey]

No description provided.

[gerrod3]

@ggainey We are going to need to add a check in modelresources.py in each foreign key widget's render method to check if value is None and return "" since that is what the parent ForeignKeyWidget does.

Or you could set the field="digest" parameter when initializing the widgets and remove the custom render method.

[ggainey]

Needs #2141 before import/export will work reliably under d-i-e/4.x

[ggainey]

#2141 is merged, the azure failure is unrelated to core/3.100 - we can force-merge this once approved, and then do a CI-Update to fix/pin azure.