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>

Author: Arielwyy

parser-Go/uast/asttype.go

@@ -3,7 +3,6 @@
 package uast
 
 type Position struct {
-	Offset int // offset, starting at 0
 	Line   int `json:"line"`   // line number, starting at 1
 	Column int `json:"column"` // column number, starting at 1 (byte count)
 }