xtask: Allow clippy::collapsible_if lint

Let-chains are being stabilized in 1.88, so this lint triggers on nightly. Since
current stable is 1.87, we can't change the code to fix this lint, and we also
can't use `expect` here. For now, the best solution is just to allow the lint.

Author: nicholasbishop

xtask/src/main.rs

@@ -1,5 +1,7 @@
 // SPDX-License-Identifier: MIT OR Apache-2.0
 
+#![allow(clippy::collapsible_if)]
+
 mod arch;
 mod cargo;
 mod check_raw;