Add PYI034 for flake8-pyi plugin (#4764)

crates/ruff_python_semantic/src/analyze/visibility.rs

@@ -89,6 +89,14 @@ pub fn is_property(
             })
     })
 }
+
+/// Returns `true` if a class is an `final`.
+pub fn is_final(model: &SemanticModel, decorator_list: &[Expr]) -> bool {
+    decorator_list
+        .iter()
+        .any(|expr| model.match_typing_expr(map_callable(expr), "final"))
+}
+
 /// Returns `true` if a function is a "magic method".
 pub fn is_magic(name: &str) -> bool {
     name.starts_with("__") && name.ends_with("__")

crates/ruff_python_semantic/src/model.rs

@@ -93,6 +93,10 @@ impl<'a> SemanticModel<'a> {
             return true;
         }
 
+        if call_path.as_slice() == ["_typeshed", target] {
+            return true;
+        }
+
         if TYPING_EXTENSIONS.contains(target) {
             if call_path.as_slice() == ["typing_extensions", target] {
                 return true;