fix: address deprecation warnings and install ghc

Signed-off-by: Lander Van den Bulcke <landervandenbulcke@gmail.com>

config/plugins/cmp/lspkind.nix

@@ -1,10 +1,7 @@
 {
   plugins.lspkind = {
     enable = true;
-    symbolMap = {
-      Copilot = " ";
-    };
-    extraOptions = {
+    settings = {
       maxwidth = 50;
       ellipsis_char = "...";
     };

config/plugins/lsp/lsp.nix

@@ -49,6 +49,7 @@
         };
         hls = {
           enable = true;
+          installGhc = true;
         };
         rubocop = {
           enable = true;