mate.engrampa: 1.20.1 -> 1.21.0

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

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

These checks were done:

- built on NixOS
- /nix/store/i4q1p8riifm6q5i7bh1yp2l53njqp2hj-engrampa-1.21.0/bin/engrampa passed the binary check.
- /nix/store/i4q1p8riifm6q5i7bh1yp2l53njqp2hj-engrampa-1.21.0/bin/.engrampa-wrapped passed the binary check.
- 2 of 2 passed binary check by having a zero exit code.
- 0 of 2 passed binary check by having the new version present in output.
- found 1.21.0 with grep in /nix/store/i4q1p8riifm6q5i7bh1yp2l53njqp2hj-engrampa-1.21.0
- directory tree listing: https://gist.github.com/a6b7848a52351898d1cac7b0baea4969
- du listing: https://gist.github.com/26e3dad544ee68b07906a4bfe1502cdc