python3Packages.black: 20.8b1 → 21.4b0

[milibopp]

Motivation for this change

Update to newly released version.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[milibopp]

Not sure where the new test failures come from and did not bother to dive into it, when I noticed some not-quite-what-we-want comment in the failing test code. The tool seems to work fine, as far as I can tell.

[sveitser]

There is already an open PR for this update #120684 .