Switch to nixpkgs-26.05-darwin stable branch (#26)

Nixpkgs 26.11 has dropped support for x86_64-darwin, so switch to the
26.05 stable branch which still has support for it.

Author: sgt0

.github/workflows/ci.yml

@@ -99,7 +99,7 @@ jobs:
       - name: Install Nix
         uses: cachix/install-nix-action@v31
         with:
-          nix_path: nixpkgs=channel:nixos-unstable
+          nix_path: nixpkgs=channel:nixpkgs-26.05-darwin
 
       - name: Set up Nix cache
         uses: cachix/cachix-action@v17
@@ -111,8 +111,8 @@ jobs:
 
       - name: Repair wheel
         run: |
-          nix shell .#llvm_${{ matrix.llvm }}.dist nixpkgs#uv \
-            --command uvx --from delocate delocate-wheel -v -w dist result-dist/*.whl
+          nix shell .#llvm_${{ matrix.llvm }}.dist \
+            --command nix develop --command uvx --from delocate delocate-wheel -v -w dist result-dist/*.whl
 
       - name: Upload
         uses: actions/upload-artifact@v7.0.1

flake.lock

@@ -1,6 +1,6 @@
 {
   inputs = {
-    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-26.05-darwin";
     flake-utils.url = "github:numtide/flake-utils";
   };
 
@@ -21,6 +21,10 @@
           default = llvm_22;
         };
 
+        devShells.default = pkgs.mkShellNoCC {
+          packages = [pkgs.uv];
+        };
+
         formatter = pkgs.alejandra;
       }
     );