mpvScripts.twitch-chat: treat script as directory-packaged

Removes the screenshot from the source archive,
to avoid wasting space in the build cache and
in outputs downloaded by end-users.

pkgs/applications/video/mpv/scripts/twitch-chat.nix

@@ -13,14 +13,12 @@ buildLua {
     owner = "CrendKing";
     repo = "mpv-twitch-chat";
     rev = "bb0c2e84675f4f1e0c221c8e1d3516b60242b985";
-    hash = "sha256-WyNPUiAs5U/vrjNbAgyqkfoxh9rabLmuZ1zG5uZYxaw=";
+    hash = "sha256-lnWYcr49koI60Su85OWbcxrARWTfXW2zIvfCZ6c3GtI=";
+
+    postFetch = "rm $out/screenshot.webp";
   };
 
-  installPhase = ''
-    runHook preInstall
-    install -D main.lua $out/share/mpv/scripts/twitch-chat.lua
-    runHook postInstall
-  '';
+  scriptPath = ".";
 
   runtime-dependencies = [ curl ];