add setup function

colors/lupan.lua

@@ -1,7 +1,7 @@
 vim.g.colors_name = 'lupan'
 if vim.o.background == "dark" then
-    package.loaded["lupancolors.lupan"] = nil
-    require("lush")(require("lupancolors.lupan"))
+    package.loaded["lupancolors.lupandark"] = nil
+    require("lush")(require("lupancolors.lupandark"))
 else
     package.loaded["lupancolors.lupanlight"] = nil
     require("lush")(require("lupancolors.lupanlight"))