xso-proc: Fix all clippy warnings

xso-proc/src/field.rs

@@ -350,9 +350,6 @@ impl FieldDef {
 
     /// Return true if this field's parsing consumes text data.
     pub(crate) fn is_text_field(&self) -> bool {
-        match self.kind {
-            FieldKind::Text { .. } => true,
-            _ => false,
-        }
+        matches!(self.kind, FieldKind::Text { .. })
     }
 }