libskk: 1.0.3 -> 1.0.4 (#42997)

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

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

Version release notes (from GitHub):
 * Don't consume key release events [#52]
 * Improve hankaku katakana conversion [#51]
 * Use the same typing rule in dict-edit mode [#50]
 * Add `abort-to-latin` and `abort-to-latin-unhandled` command [#48]
 * Add more z-* shortcuts from DDSKK
 * Fix memory leak caused by Vala array conversion
 * Bump build requirements (glib >= 2.36, valadoc >= 0.40)

These checks were done:

- built on NixOS
- /nix/store/bdfn6ravpxm5qrgf8j9zfip4w98d76i9-libskk-1.0.4/bin/skk passed the binary check.
- 1 of 1 passed binary check by having a zero exit code.
- 0 of 1 passed binary check by having the new version present in output.
- found 1.0.4 with grep in /nix/store/bdfn6ravpxm5qrgf8j9zfip4w98d76i9-libskk-1.0.4
- directory tree listing: https://gist.github.com/5b1ab808d49b2ef79a30b2188305f5e4
- du listing: https://gist.github.com/3dc4ba1b5b8124a3ac41c17b89fb5260