fix(util): normalize paths returned by Util.file_patterns (#35)

Astronvim errors while loading neoconf with neovim v0.10. The issue
appears to be the same as:
NvChad/NvChad#1832
neovim/neovim#22698

Normalizing the paths eliminates the error, but I haven't done much
testing beyond that.

lua/neoconf/util.lua

@@ -96,7 +96,7 @@ function M.file_patterns(opts)
     end
   end
 
-  return ret
+  return vim.tbl_map(vim.fs.normalize, ret)
 end
 
 ---@return { pattern: table<string, string>, filename: table<string, string> }