style: update module requires to use lowercase notation

init.lua

@@ -1,7 +1,7 @@
-require('core.options')
-require('core.functions')
-require('core.keys')
-require('core.autocmd')
-require('plugins.lazy')
+require("core.options")
+require("core.functions")
+require("core.keys")
+require("core.autocmd")
+require("plugins.lazy")
 -- Add user configs to this module
-pcall(require, 'user')
+pcall(require, "user")