Fix Lehmer64 implementation of next. (#2912)

The implementation of [`Lehmer64Rand::next`] performs a mul on `u128`, which
is not checked against overflows. It leads to panic in debug mode.


[`Lehmer64Rand`]: fd6271fa35/libafl_bolts/src/rands/mod.rs (L373-L376)

Co-authored-by: Dongjia "toka" Zhang <tokazerkje@outlook.com>

libafl_bolts/src/rands/mod.rs

@@ -371,7 +371,7 @@ impl Rand for Lehmer64Rand {
     #[inline]
     #[expect(clippy::unreadable_literal)]
     fn next(&mut self) -> u64 {
-        self.s *= 0xda942042e4dd58b5;
+        self.s = self.s.wrapping_mul(0xda942042e4dd58b5);
         (self.s >> 64) as u64
     }
 }