Use https for flake

flake.nix

@@ -21,7 +21,7 @@
     };
 
     ai-usage = {
-      url = "git+ssh://git@git.een.ninja:222/armel/ai-usage.git";
+      url = "git+https://git.een.ninja/armel/ai-usage.git";
       inputs.nixpkgs.follows = "nixpkgs";
     };
   };