Ignore items_after_statements Clippy pedantic lint in test

    error: adding items after statements is confusing, since items exist from the start of the scope
       --> tests/test_ensure.rs:324:5
        |
    324 | /     enum E<'a, T> {
    325 | |         #[allow(dead_code)]
    326 | |         T(&'a T),
    327 | |         U,
    328 | |     }
        | |_____^
        |
        = note: `-D clippy::items-after-statements` implied by `-D clippy::pedantic`
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#items_after_statements

tests/test_ensure.rs

@@ -2,6 +2,7 @@
     clippy::diverging_sub_expression,
     clippy::if_same_then_else,
     clippy::ifs_same_cond,
+    clippy::items_after_statements,
     clippy::let_and_return,
     clippy::let_underscore_drop,
     clippy::match_bool,