refactor devShell in the flake

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

flake.lock

@@ -2,16 +2,16 @@
   "nodes": {
     "nixpkgs": {
       "locked": {
-        "lastModified": 1648632716,
-        "narHash": "sha256-kCmnDeiaMsdhfnNKjxdOzwRh2H6eQb8yWAL+nNabC/Y=",
+        "lastModified": 1666393929,
+        "narHash": "sha256-Tet6WIaK0NaeNmr+0ayIkHEauuKde+Tv3X+giSQB6wE=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "710fed5a2483f945b14f4a58af2cd3676b42d8c8",
+        "rev": "7a0b1f3b9549507ba45339178221e6494f5ab6d7",
         "type": "github"
       },
       "original": {
         "owner": "nixos",
-        "ref": "nixos-unstable",
+        "ref": "release-22.05",
         "repo": "nixpkgs",
         "type": "github"
       }
@@ -24,11 +24,11 @@
     },
     "utils": {
       "locked": {
-        "lastModified": 1648297722,
-        "narHash": "sha256-W+qlPsiZd8F3XkzXOzAoR+mpFqzm3ekQkJNa+PIh1BQ=",
+        "lastModified": 1659877975,
+        "narHash": "sha256-zllb8aq3YO3h8B/U0/J1WBgAL8EX5yWf5pMj3G0NAmc=",
         "owner": "numtide",
         "repo": "flake-utils",
-        "rev": "0f8662f1319ad6abf89b3380dd2722369fc51ade",
+        "rev": "c0e246b9b83f637f4681389ecabcb2681b4f3af0",
         "type": "github"
       },
       "original": {