refactor: move Day struct to template module (#40)

src/template/commands/solve.rs

@@ -1,6 +1,6 @@
 use std::process::{Command, Stdio};
 
-use crate::Day;
+use crate::template::Day;
 
 pub fn handle(day: Day, release: bool, time: bool, submit_part: Option<u8>) {
     let mut cmd_args = vec!["run".to_string(), "--bin".to_string(), day.to_string()];