feat: Install weechat-matrix

based on the input provided by @mjlbach in
NixOS/nixpkgs#79646 (comment)

Author: vidbina

chat.nix

@@ -5,11 +5,12 @@ let
     configure = { availablePlugins, ... }: {
       plugins = with availablePlugins; [
         (perl.withPackages (p: [ p.PodParser ]))
-        python
+        (python.withPackages (_: with weechatScripts; [ weechat-matrix ]))
       ];
       scripts = with weechatScripts; [
         wee-slack
         weechat-autosort
+        weechat-matrix
       ];
     };
   };