fix(macros): resolve clippy lint warning

cc rust-lang/rust-clippy#5849 Signed-off-by: Austin Bonander <austin@launchbadge.com>

Author: abonander

sqlx-macros/src/query/args.rs

@@ -29,7 +29,7 @@ pub fn quote_args<DB: DatabaseExt>(
  let arg_expr = input.arg_exprs.iter().cloned().map(strip_wildcard);
 
  let arg_bindings = quote! {
- #(let ref #arg_name = #arg_expr;)*
+ #(let #arg_name = &(#arg_expr);)*
  };
 
  let args_check = match info.parameters() {