Martellus Bennett of Green Bay Packers says he’s ‘pretty sure’ he’ll retire after this season

GREEN BAY, Wis. — When veteran tight end Martellus Bennett signed a three-year, $21 million contract with the Green Bay Packers this spring, he never offered any hint that his stay would be much shorter.

But Bennett might be calling it quits after just one year in Green Bay.

Bennett, 30, posted an Instagram story on Saturday saying he is considering retirement after this season, his 10th…