Fix new clippy lint

Author: GuillaumeGomez

askama_derive/src/input.rs

@@ -673,20 +673,15 @@ pub(crate) enum Source {
     Source(Arc<str>),
 }
 
-#[derive(Clone, Copy, Debug, PartialEq, Hash)]
+#[derive(Clone, Copy, Debug, PartialEq, Hash, Default)]
 pub(crate) enum Print {
     All,
     Ast,
     Code,
+    #[default]
     None,
 }
 
-impl Default for Print {
-    fn default() -> Self {
-        Self::None
-    }
-}
-
 impl FromStr for Print {
     type Err = String;