flake.lock: Update

Flake lock file updates:

• Updated input 'nix-super/nixpkgs':
    follows 'nixpkgs'
  → 'github:NixOS/nixpkgs/530a53dcbc9437363471167a5e4762c5fcfa34a1' (2022-02-19)

flake.lock

@@ -482,9 +482,7 @@
     "nix-super": {
       "inputs": {
         "lowdown-src": "lowdown-src_2",
-        "nixpkgs": [
-          "nixpkgs"
-        ],
+        "nixpkgs": "nixpkgs_5",
         "nixpkgs-regression": "nixpkgs-regression"
       },
       "locked": {
@@ -580,6 +578,21 @@
       }
     },
     "nixpkgs_5": {
+      "locked": {
+        "lastModified": 1645296114,
+        "narHash": "sha256-y53N7TyIkXsjMpOG7RhvqJFGDacLs9HlyHeSTBioqYU=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "530a53dcbc9437363471167a5e4762c5fcfa34a1",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "ref": "nixos-21.05-small",
+        "type": "indirect"
+      }
+    },
+    "nixpkgs_6": {
       "locked": {
         "lastModified": 1653819559,
         "narHash": "sha256-KzIZ1uaLR7vsBlcT0VWd8toFTC3yunSveNK+l2MQqrI=",
@@ -688,7 +701,7 @@
         "mms": "mms",
         "nar-serve": "nar-serve",
         "nix-super": "nix-super",
-        "nixpkgs": "nixpkgs_5"
+        "nixpkgs": "nixpkgs_6"
       }
     },
     "utils": {