Remove Expr.__iadd__ stub

Author: jonathanberthias

src/pyscipopt/scip.pyi

@@ -389,12 +389,6 @@ class Expr(ExprLike):
     def __add__(self, other: np.ndarray | MatrixExpr, /) -> MatrixExpr: ...
     def __radd__(self, other: float, /) -> Expr: ...
     @overload
-    def __iadd__(self, other: float | Expr, /) -> Expr: ...  # noqa: PYI034
-    @overload
-    def __iadd__(self, other: GenExpr, /) -> SumExpr: ...
-    @overload
-    def __iadd__(self, other: np.ndarray | MatrixExpr, /) -> MatrixExpr: ...
-    @overload
     def __sub__(self, other: float | Expr, /) -> Expr: ...
     @overload
     def __sub__(self, other: GenExpr, /) -> SumExpr: ...