Solved hw1/task1 and passed all tests

hw1/task1/Cargo.toml

+[package]
+name = "task1"
+version = "0.1.0"
+authors = ["Joshua Rutschmann <joshua.rutschmann@gmx.de>"]
+
+[dependencies]

hw1/task1/src/lib.rs

 pub fn is_leap_year(year: i32) -> bool {
-    unimplemented!();
+    (year % 4 == 0 && year % 100 != 0) || year % 400 == 0
 }