Merge branch 'update-nixpkgs' into 'develop'

Update nixpkgs.

See merge request privatestorage/PrivateStorageio!219

nixpkgs-2105.json

 {
   "name": "release2105",
-  "url": "https://releases.nixos.org/nixos/21.05/nixos-21.05.4044.e74894146a4/nixexprs.tar.xz",
-  "sha256": "1f13if5pkr7xz5wsfrwvr9k498l6kd24625ppsrc0bmdq144ij12"
+  "url": "https://releases.nixos.org/nixos/21.05/nixos-21.05.4114.195d5816cdd/nixexprs.tar.xz",
+  "sha256": "1074fy0as55vxqy36rqs33hvdqf92ys5di6ij826h34b5qvcfjkm"
 }
\ No newline at end of file