freecell-solver: 4.16.0 -> 4.18.0

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

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

These checks were done:

- built on NixOS
- ran `/nix/store/k186rg37jwk63hvw2h1nmpmssa3cwrj4-freecell-solver-4.18.0/bin/fc-solve -h` got 0 exit code
- ran `/nix/store/k186rg37jwk63hvw2h1nmpmssa3cwrj4-freecell-solver-4.18.0/bin/fc-solve --help` got 0 exit code
- ran `/nix/store/k186rg37jwk63hvw2h1nmpmssa3cwrj4-freecell-solver-4.18.0/bin/fc-solve --version` and found version 4.18.0
- ran `/nix/store/k186rg37jwk63hvw2h1nmpmssa3cwrj4-freecell-solver-4.18.0/bin/pi-make-microsoft-freecell-board -h` got 0 exit code
- ran `/nix/store/k186rg37jwk63hvw2h1nmpmssa3cwrj4-freecell-solver-4.18.0/bin/pi-make-microsoft-freecell-board --help` got 0 exit code
- ran `/nix/store/k186rg37jwk63hvw2h1nmpmssa3cwrj4-freecell-solver-4.18.0/bin/pi-make-microsoft-freecell-board help` got 0 exit code
- ran `/nix/store/k186rg37jwk63hvw2h1nmpmssa3cwrj4-freecell-solver-4.18.0/bin/fc_solve_find_index_s2ints.py -h` got 0 exit code
- ran `/nix/store/k186rg37jwk63hvw2h1nmpmssa3cwrj4-freecell-solver-4.18.0/bin/fc_solve_find_index_s2ints.py --help` got 0 exit code
- ran `/nix/store/k186rg37jwk63hvw2h1nmpmssa3cwrj4-freecell-solver-4.18.0/bin/fc_solve_find_index_s2ints.py help` got 0 exit code
- found 4.18.0 with grep in /nix/store/k186rg37jwk63hvw2h1nmpmssa3cwrj4-freecell-solver-4.18.0
- directory tree listing: https://gist.github.com/2c22e8a4355b2da3c90bfde6c8d92c13