style: change double quotes to single

Author: Joshua Molloy

lua/custom/plugins/init.lua

@@ -11,5 +11,5 @@ return {
       vim.cmd.colorscheme 'moonfly'
     end,
   },
-  { "nvim-neotest/nvim-nio" }
+  { 'nvim-neotest/nvim-nio' },
 }