alacritty: only build on linux

the darwin build fails at the moment and since we are now using patchelf
it would not build anyway.

pkgs/applications/misc/alacritty/default.nix

@@ -62,6 +62,6 @@ buildRustPackage rec {
     homepage = https://github.com/jwilm/alacritty;
     license = with licenses; [ asl20 ];
     maintainers = with maintainers; [ mic92 ];
-    platforms = platforms.all;
+    platforms = platforms.linux;
   };
 }