add env_logger in cli version

crates/unitdc-cli/Cargo.toml

@@ -6,4 +6,5 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+env_logger = "0.10.0"
 unitdc = { path = "../../" }

crates/unitdc-cli/src/main.rs

@@ -1,6 +1,7 @@
 use unitdc::interpreter::{Interpreter, Output};
 
 fn main() {
+    env_logger::init();
     let mut interpreter = Interpreter::new(Box::new(|output| match output {
         Output::Message(e) => eprintln!("message: {}", e),
         Output::Quantity(q) => println!("[0]: {}", q),