Add riscv64-linux to supported systems

Author: 0x4A6F

flake.nix

@@ -153,7 +153,7 @@
     };
     overlays.default = overlay;
   } //
-    utils.lib.eachSystem (utils.lib.defaultSystems ++ ["aarch64-darwin"]) (system:
+    utils.lib.eachSystem (utils.lib.defaultSystems ++ ["aarch64-darwin" "riscv64-linux"]) (system:
       let
         pkgs = import nixpkgs {
           inherit system;