Revert "feat: GHViewWeb uses "open" under macOS"

This reverts commit e69587f.

Author: ldelossa

lua/litee/gh/pr/init.lua

@@ -22,11 +22,7 @@ local M = {}
 M.autocmds = {}
 
 local function open_nodes_url(node)
-    if vim.fn.has('mac') then
-        vim.fn.system({'open', node.url})
-    else
-        vim.fn.system({'xdg-open', node.url})
-    end
+    vim.fn.system({'xdg-open', node.url})
 end
 
 local function ui_req_ctx()