nix: Fix dev shell on Darwin (#58032)

Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [ ] Unsafe blocks (if any) have justifying comments
- [ ] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [ ] Tests cover the new/changed behavior
- [ ] Performance impact has been considered and is acceptable

Release Notes:

- N/A

nix/modules/devshells.nix

@@ -37,30 +37,32 @@
         name = "zed-editor-dev";
         inputsFrom = [ zed-editor ];
 
-        packages = with pkgs; [
-          wrappedCargo # must be first, to shadow the `cargo` provided by `rustToolchain`
-          rustToolchain # cargo, rustc, and rust-toolchain.toml components included
-          cargo-nextest
-          cargo-hakari
-          cargo-machete
-          cargo-zigbuild
-          # TODO: package protobuf-language-server for editing zed.proto
-          # TODO: add other tools used in our scripts
+        packages =
+          with pkgs;
+          [
+            wrappedCargo # must be first, to shadow the `cargo` provided by `rustToolchain`
+            rustToolchain # cargo, rustc, and rust-toolchain.toml components included
+            cargo-nextest
+            cargo-hakari
+            cargo-machete
+            cargo-zigbuild
+            # TODO: package protobuf-language-server for editing zed.proto
+            # TODO: add other tools used in our scripts
 
-          # `build.nix` adds this to the `zed-editor` wrapper (see `postFixup`)
-          # we'll just put it on `$PATH`:
-          nodejs_22
-          zig
+            # `build.nix` adds this to the `zed-editor` wrapper (see `postFixup`)
+            # we'll just put it on `$PATH`:
+            nodejs_22
+            zig
 
-          # A11y testing infra
-          gobject-introspection 
-          at-spi2-core 
-          (python3.withPackages (ps: [
-            ps.pyatspi
-            ps.pygobject3
-          ]))
-          accerciser
-        ];
+            # A11y testing infra
+            gobject-introspection
+            at-spi2-core
+            (python3.withPackages (ps: [
+              ps.pyatspi
+              ps.pygobject3
+            ]))
+          ]
+          ++ lib.optionals stdenv.hostPlatform.isLinux [ accerciser ];
 
         env =
           (removeAttrs baseEnv [