Split types as advised by rust-clippy

rust/src/main.rs

@@ -9,7 +9,9 @@ use rstest::rstest;
 mod p0001;
 mod p0002;
 
-const ANSWERS: [(&str, fn() -> u64, u64); 2] = [
+type ProblemType = fn() -> u64;
+type ProblemRef = (&str, ProblemType, u64);
+const ANSWERS: [ProblemRef; 2] = [
     ("p0001", p0001::p0001, 233168),
     ("p0002", p0002::p0002, 4613732)
 ];