Added missing espeak-ng dependency

default.nix

@@ -1,4 +1,4 @@
-{ lib, python311Packages }:
+{ lib, python311Packages, pkgs }:
 with python311Packages;
 let
   # Stripped down version of the tts package (original is broken and needs cuda)
@@ -15,6 +15,8 @@ let
       };
       doCheck = false;
 
+      nativeBuildInputs = [ pkgs.espeak-ng ];
+
       dependencies = [
         cython
         numpy
@@ -34,6 +36,7 @@ let
         jamo
         jieba
         pypinyin
+        pkgs.espeak
       ];
     };
 in