flake: pin mu to 1.6.11

Waiting for Doom Emacs to support 1.8.x

flake.lock

@@ -88,6 +88,22 @@
         "type": "github"
       }
     },
+    "nixpkgs-mu-1-6-11": {
+      "locked": {
+        "lastModified": 1656166034,
+        "narHash": "sha256-r3v8um8KLJVm1XFGmovKeEBUtdoSTOWP+qKJztIbERQ=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "0100c5e564462ca83aed241c58a3427783737a26",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "0100c5e564462ca83aed241c58a3427783737a26",
+        "type": "github"
+      }
+    },
     "nixpkgs-unstable-small": {
       "locked": {
         "lastModified": 1656243367,
@@ -127,6 +143,7 @@
         "home-manager": "home-manager",
         "nixos-hardware": "nixos-hardware",
         "nixpkgs": "nixpkgs_2",
+        "nixpkgs-mu-1-6-11": "nixpkgs-mu-1-6-11",
         "nixpkgs-unstable-small": "nixpkgs-unstable-small"
       }
     },

flake.nix

@@ -8,6 +8,13 @@
       ref = "nixos-unstable";
     };
 
+    nixpkgs-mu-1-6-11 = {
+        type = "github";
+        owner = "NixOS";
+        repo = "nixpkgs";
+        rev = "0100c5e564462ca83aed241c58a3427783737a26";
+    };
+
     nixpkgs-unstable-small = {
       type = "github";
       owner = "NixOS";
@@ -74,6 +81,7 @@
           [
             (self: super: {
               packages = import ./pkgs {pkgs = super;};
+              mu = (import inputs.nixpkgs-mu-1-6-11 { inherit system; }).mu;
 
               # packages accessible through pkgs.unstable.package
               unstable = import inputs.nixpkgs-unstable-small {