refactor: fix most pedantic clippy warnings

closes #29

Co-authored-by: Andy Pymont <andypymont@gmail.com>

src/template/commands/download.rs

@@ -1,14 +1,14 @@
 use crate::template::aoc_cli;
 use std::process;
 
-pub fn download_handler(day: u8) {
+pub fn handle(day: u8) {
     if aoc_cli::check().is_err() {
         eprintln!("command \"aoc\" not found or not callable. Try running \"cargo install aoc-cli\" to install it.");
         process::exit(1);
     }
 
     if let Err(e) = aoc_cli::download(day) {
-        eprintln!("failed to call aoc-cli: {}", e);
+        eprintln!("failed to call aoc-cli: {e}");
         process::exit(1);
     };
 }