Hi there,

Is there any reason for this upperbound?

https://github.com/allegroai/clearml-agent/blob/e3e6a1dda81bee2dd20a64d09746568e415f1823/requirements.txt#L1

Looking at the release log I don't think clearml-agent will be affected by any of the breaking changes, but I'm not an expert!

If it can be upgraded to attrs>=18.0,<21.5.0 I'll make a PR.