fix clippy warnings

src/assembler.rs

@@ -140,6 +140,12 @@ impl Assembler {
     }
 }
 
+impl Default for Assembler {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 fn parse_u128(src: &str) -> Result<u128, Box<dyn Error>> {
     if let Some(s) = src.strip_prefix("0b") {
         Ok(u128::from_str_radix(s, 2)?)