Github workflows for code formatting sometimes fail unexpectedly

[snukky]

Describe the bug

The code formatting validations are currently not working properly. MyPy checks seem to always fail due to a known bug. A solution is to upgrade MyPy, but Python 3.10 should not be used in any of the jobs as we test only Python 3.6-3.9.

Also, it might not be deterministic, because a recent PR merge passed the tests normally.

To Reproduce Steps to reproduce the behavior: Run

Additional context

• https://github.com/AppraiseDev/Appraise/actions/runs/3252917786/jobs/5351356848
• https://github.com/AppraiseDev/Appraise/pull/97#issuecomment-1279849767

[snukky]

This might be nondeterministic (maybe depending on the VM assigned?) because https://github.com/AppraiseDev/Appraise/actions/runs/3271987621 passed without any changes to the workflow, AFAIK.

[hitokazm]

Is there any way to fix the python version for a docker image running code format validation?