clippy: if_then_panic is no longer enabled by default (also changed name)

Author: bluss

src/lib.rs

@@ -15,7 +15,6 @@
     clippy::manual_map, // is not an error
     clippy::while_let_on_iterator, // is not an error
     clippy::from_iter_instead_of_collect, // using from_iter is good style
-    clippy::if_then_panic, // is not an error
     clippy::redundant_closure, // false positives clippy #7812
 )]
 #![doc(test(attr(deny(warnings))))]