python3Packages.nbval: Skip failing tests

[acairncross]

ZHF: #122042

Motivation for this change

matplotlib likes to print warnings and the nbval tests are picky about there being no warnings. In this case matplotlib prints deprecation warnings because our version of IPython is too old and is calling deprecated matplotlib functions (see here for an actual solution: computationalmodelling/nbval#167). This isn't the first time these tests have failed because of matplotlib warnings so it's easiest to just skip them.

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/)
• Added a release notes entry if the change is major or breaking
• Fits CONTRIBUTING.md.

@NixOS/nixos-release-managers

[r-rmcgibbo]

Result of nixpkgs-review pr 123921 at 455832e run on aarch64-linux 1

6 packages built successfully:

• python38Packages.ipydatawidgets
• python38Packages.nbval
• python38Packages.onnx
• python39Packages.ipydatawidgets
• python39Packages.nbval
• python39Packages.onnx

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Result of nixpkgs-review pr 123921 at 455832e run on x86_64-linux 1

6 packages built successfully:

• python38Packages.ipydatawidgets
• python38Packages.nbval
• python38Packages.onnx
• python39Packages.ipydatawidgets
• python39Packages.nbval
• python39Packages.onnx