mkvtoolnix: 9.4.2 -> 9.5.0

[romildo]

Motivation for this change

MKVToolNix v9.5.0 released

Things done

• Tested using sandboxing
  (nix.useSandbox on NixOS,
  or option build-use-sandbox in nix.conf
  on non-NixOS)
• Built on platform(s)
  • NixOS
  • OS X
  • Linux
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.

[mention-bot]

@romildo, thanks for your PR! By analyzing the history of the files in this pull request, we identified @rnhmjoj, @dguibert and @codyopel to be potential reviewers.

[NeQuissimus]

Did you execute the binary to make sure it works?

[romildo]

I have executed the binary, and the GUI opens without problems. But I did not extensively test the functionality of the GUI, as there are many things it can do.