Remove fira-code symbol configuration on mac

This unfortunately is not working. Unsure if because of the newer version of
fira code that I am using from homebrew, or because of a mac incompatibility.

config.d/fira-code.el

@@ -130,5 +130,6 @@
 (defun add-fira-code-symbol-keywords ()
   (font-lock-add-keywords nil fira-code-font-lock-keywords-alist))
 
-(add-hook 'prog-mode-hook
-          #'add-fira-code-symbol-keywords)
+(when (not (darwin?))
+  (add-hook 'prog-mode-hook
+            #'add-fira-code-symbol-keywords))