fixbug[parser-Go]: remove unused Offset field of Position (#46) * fixbug: add support for parsing classes with generic base types (e.g., Generic[T]) in Python UAST * fixbug: use ScopedType instead of Identifier for user-defined types in VariableDeclaration * fixbug: remove unused Offset field of Position --------- Co-authored-by: 王雅仪 <wangyayi.wyy@antgroup.com>