libressl: 2.7.3 -> 2.7.4

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

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

These checks were done:

- built on NixOS
- Warning: no invocation of /nix/store/2sj5bh1lwzls0vc31v2fhxaw648n0i9v-libressl-2.7.4-bin/bin/ocspcheck had a zero exit code or showed the expected version
- /nix/store/2sj5bh1lwzls0vc31v2fhxaw648n0i9v-libressl-2.7.4-bin/bin/openssl passed the binary check.
- 1 of 2 passed binary check by having a zero exit code.
- 1 of 2 passed binary check by having the new version present in output.
- found 2.7.4 with grep in /nix/store/2sj5bh1lwzls0vc31v2fhxaw648n0i9v-libressl-2.7.4-bin
- directory tree listing: https://gist.github.com/e28b9d47b987d9408427c7ec06e3b9fb
- du listing: https://gist.github.com/0d61c26c272780f10c5ce5359fb79bc7