Bump to PaymentServer 2022-01-17

Changes - https://github.com/PrivateStorageio/PaymentServer/compare/e080beb14ec58ffe8e55c35e6dddd46c5082887f...47478f705332b23219285e9598a69668f2c79aa1

• Update Haskell.nix / NixOS to 21.11
  • Packaging changes for compatibility with this
• Non-production CI changes
• New get-public-key tool (not part of deployment)