fix: simplify condition by checking refutability for inner pattern only

Author: a-yossy

clippy_lints/src/loops/manual_flatten.rs

@@ -37,9 +37,7 @@ pub(super) fn check<'tcx>(
         // Ensure expr in `if let` is not used afterwards
         && !is_local_used(cx, if_then, pat_hir_id)
         && msrv.meets(cx, msrvs::ITER_FLATTEN)
-        && pats.iter().all(|pat| {
-            !is_refutable(cx, pat)
-        })
+        && !is_refutable(cx, inner_pat)
     {
         let if_let_type = if some_ctor { "Some" } else { "Ok" };
         // Prepare the error message