Use numtide/devshell instead of pkgs.mkShell

flake.lock

@@ -42,6 +42,27 @@
         "type": "github"
       }
     },
+    "devshell": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": [
+          "nixpkgs-unstable"
+        ]
+      },
+      "locked": {
+        "lastModified": 1644227066,
+        "narHash": "sha256-FHcFZtpZEWnUh62xlyY3jfXAXHzJNEDLDzLsJxn+ve0=",
+        "owner": "numtide",
+        "repo": "devshell",
+        "rev": "7033f64dd9ef8d9d8644c5030c73913351d2b660",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "devshell",
+        "type": "github"
+      }
+    },
     "flake-compat": {
       "flake": false,
       "locked": {
@@ -59,6 +80,21 @@
       }
     },
     "flake-utils": {
+      "locked": {
+        "lastModified": 1642700792,
+        "narHash": "sha256-XqHrk7hFb+zBvRg6Ghl+AZDq03ov6OshJLiSWOoX5es=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "846b2ae0fc4cc943637d3d1def4454213e203cba",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "flake-utils_2": {
       "locked": {
         "lastModified": 1644229661,
         "narHash": "sha256-1YdnJAsNy69bpcjuoKdOYQX0YxZBiCYZo4Twxerqv7k=",
@@ -208,7 +244,8 @@
       "inputs": {
         "agenix": "agenix",
         "deploy-rs": "deploy-rs",
-        "flake-utils": "flake-utils",
+        "devshell": "devshell",
+        "flake-utils": "flake-utils_2",
         "home-manager": "home-manager",
         "impermanence": "impermanence",
         "nix": "nix",