pari: 2.9.3 -> 2.9.4

Semi-automatic update. These checks were performed:

- built on NixOS
- ran `/nix/store/v2rvjr4kl79kmn1w70lj7zf0dz00p3mf-pari-2.9.4/bin/tex2mail help` got 0 exit code
- ran `/nix/store/v2rvjr4kl79kmn1w70lj7zf0dz00p3mf-pari-2.9.4/bin/gphelp --help` got 0 exit code
- ran `/nix/store/v2rvjr4kl79kmn1w70lj7zf0dz00p3mf-pari-2.9.4/bin/gphelp help` got 0 exit code
- ran `/nix/store/v2rvjr4kl79kmn1w70lj7zf0dz00p3mf-pari-2.9.4/bin/gp-2.9 -h` got 0 exit code
- ran `/nix/store/v2rvjr4kl79kmn1w70lj7zf0dz00p3mf-pari-2.9.4/bin/gp-2.9 --help` got 0 exit code
- ran `/nix/store/v2rvjr4kl79kmn1w70lj7zf0dz00p3mf-pari-2.9.4/bin/gp-2.9 -V` and found version 2.9.4
- ran `/nix/store/v2rvjr4kl79kmn1w70lj7zf0dz00p3mf-pari-2.9.4/bin/gp-2.9 -v` and found version 2.9.4
- ran `/nix/store/v2rvjr4kl79kmn1w70lj7zf0dz00p3mf-pari-2.9.4/bin/gp-2.9 --version` and found version 2.9.4
- ran `/nix/store/v2rvjr4kl79kmn1w70lj7zf0dz00p3mf-pari-2.9.4/bin/gp-2.9 -h` and found version 2.9.4
- ran `/nix/store/v2rvjr4kl79kmn1w70lj7zf0dz00p3mf-pari-2.9.4/bin/gp-2.9 --help` and found version 2.9.4
- found 2.9.4 with grep in /nix/store/v2rvjr4kl79kmn1w70lj7zf0dz00p3mf-pari-2.9.4
- found 2.9.4 in filename of file in /nix/store/v2rvjr4kl79kmn1w70lj7zf0dz00p3mf-pari-2.9.4

cc "@ertes @raskin @AndersonTorres"