fix: exclude deleted bird tool from tools bundle

The steipete/bird GitHub repo was deleted, causing release asset
downloads to 404 and breaking the tools derivation.

Cherry-picked from openclaw#63.
See: openclaw/nix-steipete-tools#6

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: zsoerenm

flake.nix

@@ -48,6 +48,9 @@
           pkgs = pkgs;
           sourceInfo = sourceInfoStable;
           steipetePkgs = steipetePkgs;
+          # bird: upstream repo steipete/bird deleted, release assets 404.
+          # https://github.com/openclaw/nix-steipete-tools/issues/6
+          excludeToolNames = [ "bird" ];
         };
       in
       {