I apologize upfront that I don't have know what the root cause of the problem is because I don't know much about the changes between 0.14.1 and 0.15.0.

Here's the failure on 0.15.0: https://github.com/fastavro/fastavro/runs/1630514376?check_suite_focus=true

And here's a working install from a few days ago when it used 0.14.1: https://github.com/fastavro/fastavro/runs/1620804784?check_suite_focus=true (You'll want to look at the "Install Testing Dependencies" since that is the step that installs zstandard)

I think the main difference I can see is that version 0.14.1 had a wheel to install whereas when trying to install 0.15.0 it installs from source and fails.

Does anyone have any thoughts?