electrum-ltc: 3.1.2.1 -> 3.1.3.1 (#39440)

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

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

These checks were done:

- built on NixOS
- ran ‘/nix/store/j1k6vy1aswd5nm2h1y5b5807jwv5lvz8-electrum-ltc-3.1.3.1/bin/.electrum-ltc-wrapped -h’ got 0 exit code
- ran ‘/nix/store/j1k6vy1aswd5nm2h1y5b5807jwv5lvz8-electrum-ltc-3.1.3.1/bin/.electrum-ltc-wrapped --help’ got 0 exit code
- ran ‘/nix/store/j1k6vy1aswd5nm2h1y5b5807jwv5lvz8-electrum-ltc-3.1.3.1/bin/.electrum-ltc-wrapped help’ got 0 exit code
- ran ‘/nix/store/j1k6vy1aswd5nm2h1y5b5807jwv5lvz8-electrum-ltc-3.1.3.1/bin/electrum-ltc -h’ got 0 exit code
- ran ‘/nix/store/j1k6vy1aswd5nm2h1y5b5807jwv5lvz8-electrum-ltc-3.1.3.1/bin/electrum-ltc --help’ got 0 exit code
- ran ‘/nix/store/j1k6vy1aswd5nm2h1y5b5807jwv5lvz8-electrum-ltc-3.1.3.1/bin/electrum-ltc help’ got 0 exit code
- found 3.1.3.1 with grep in /nix/store/j1k6vy1aswd5nm2h1y5b5807jwv5lvz8-electrum-ltc-3.1.3.1
- directory tree listing: https://gist.github.com/b26f1ac3c0cbfa08852ab2610031bb4c