Add src to Settings hash

src/settings/mod.rs

@@ -283,6 +283,7 @@ impl Hash for Settings {
             }
         }
         self.show_source.hash(state);
+        self.src.hash(state);
         self.target_version.hash(state);
         // Add plugin properties in alphabetical order.
         self.flake8_annotations.hash(state);