thttpd: 2.28 -> 2.29 (#41233)

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

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

These checks were done:

- built on NixOS
- Warning: no invocation of /nix/store/hbab4sxrd03rn29fr2hzxcqhdb11ac7r-thttpd-2.29/bin/htpasswd had a zero exit code or showed the expected version
- Warning: no invocation of /nix/store/hbab4sxrd03rn29fr2hzxcqhdb11ac7r-thttpd-2.29/bin/makeweb had a zero exit code or showed the expected version
- /nix/store/hbab4sxrd03rn29fr2hzxcqhdb11ac7r-thttpd-2.29/bin/syslogtocern passed the binary check.
- /nix/store/hbab4sxrd03rn29fr2hzxcqhdb11ac7r-thttpd-2.29/bin/thttpd passed the binary check.
- 2 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 2.29 with grep in /nix/store/hbab4sxrd03rn29fr2hzxcqhdb11ac7r-thttpd-2.29
- directory tree listing: https://gist.github.com/e0eb71192cc958ded9003250a4a4f65b
- du listing: https://gist.github.com/890be31bcaa84f99915896503cde2679