Update nixpkgs-ps to include PaymentServer 0.1.1.1

... fixing the Prometheus metric names a second time.

nixpkgs-ps.json

 { "name": "nixpkgs"
-, "url": "https://github.com/PrivateStorageio/nixpkgs/archive/a5cbaadd9676e8c568061e92bbf5ad6a5d884ded.tar.gz"
-, "sha256": "0q5zknsp0qb25ag9zr9bw1ap7pb3f76bxsw81ahxkzj4z5dw6k2f"
+, "url": "https://github.com/PrivateStorageio/nixpkgs/archive/5ebd5af2d5c6caf23735c8c0e6bc27357fa8d2a8.tar.gz"
+, "sha256": "1g2bvs8prqjskzv8s1qmh36k7rmj98jib0syqbrq02xxzw5dpqb4"
 }