Merge branch 'update-nixpkgs' into 'develop'

Update nixpkgs.

See merge request !181

nixpkgs-2105.json

-{
-  "name": "release2105",
-  "url": "https://releases.nixos.org/nixos/21.05/nixos-21.05.3065.b3083bc6933/nixexprs.tar.xz",
-  "sha256": "186vni8rij8bhd6n5n9h55jf2x78v9zdy2gn9v4cpjhajp4pvzm0"
-}
+{
+  "name": "release2105",
+  "url": "https://releases.nixos.org/nixos/21.05/nixos-21.05.3367.fd8a7fd07da/nixexprs.tar.xz",
+  "sha256": "12p7v805xj5as2fbdh30i0b9iwy8y24sk256rgqfqylxj1784mn8"
+}