mate.mate-terminal: 1.20.1 -> 1.21.0 (#43180)

Semi-automatic update generated by https://github.com/ryantm/nixpkgs-update tools.

This update was made based on information from https://repology.org/metapackage/mate-terminal/versions.

These checks were done:

- built on NixOS
- /nix/store/pkwgjc2972cx5yicsppl6ivkrbl9sflh-mate-terminal-1.21.0/bin/mate-terminal passed the binary check.
- /nix/store/pkwgjc2972cx5yicsppl6ivkrbl9sflh-mate-terminal-1.21.0/bin/mate-terminal.wrapper passed the binary check.
- /nix/store/pkwgjc2972cx5yicsppl6ivkrbl9sflh-mate-terminal-1.21.0/bin/.mate-terminal-wrapped passed the binary check.
- /nix/store/pkwgjc2972cx5yicsppl6ivkrbl9sflh-mate-terminal-1.21.0/bin/.mate-terminal.wrapper-wrapped passed the binary check.
- 4 of 4 passed binary check by having a zero exit code.
- 0 of 4 passed binary check by having the new version present in output.
- found 1.21.0 with grep in /nix/store/pkwgjc2972cx5yicsppl6ivkrbl9sflh-mate-terminal-1.21.0
- directory tree listing: https://gist.github.com/cbbde60e233e1916f09d61e0a3e6e306
- du listing: https://gist.github.com/21079e9340adbd98c94647457231e080