Add missing type_params attribute for ClassDef node before 3.12

Author: SigureMo

gast/ast3.py

@@ -74,6 +74,17 @@ def visit_Bytes(self, node):
             )
             return gast.copy_location(new_node, node)
 
+        def visit_ClassDef(self, node):
+            new_node = gast.ClassDef(
+                self._visit(node.name),
+                self._visit(node.bases),
+                self._visit(node.keywords),
+                self._visit(node.body),
+                self._visit(node.decorator_list),
+                [],  # type_params
+            )
+            return gast.copy_location(new_node, node)
+
         def visit_FunctionDef(self, node):
             new_node = gast.FunctionDef(
                 self._visit(node.name),
@@ -226,6 +237,18 @@ def visit_comprehension(self, node):
             return ast.copy_location(new_node, node)
 
     if 8 <= sys.version_info.minor < 12:
+
+        def visit_ClassDef(self, node):
+            new_node = gast.ClassDef(
+                self._visit(node.name),
+                self._visit(node.bases),
+                self._visit(node.keywords),
+                self._visit(node.body),
+                self._visit(node.decorator_list),
+                [],  # type_params
+            )
+            return gast.copy_location(new_node, node)
+
         def visit_FunctionDef(self, node):
             new_node = gast.FunctionDef(
                 self._visit(node.name),