Allow no_effect lint

for cleaner stderr file

Co-Authored-By: Philipp Krones <hello@philkrones.com>

tests/ui/out_of_bounds_indexing/issue-3102.rs

@@ -1,4 +1,5 @@
 #![warn(clippy::out_of_bounds_indexing)]
+#![allow(clippy::no_effect)]
 
 fn main() {
     let x = [1, 2, 3, 4];