MADISON, Wis. — The special investigator hired by Republicans in Wisconsin to review the 2020 election told lawmakers in March that they should consider decertifying President Joe Biden’s win, but later said in a private memo made public Tuesday that such a move would be a “practical impossibility.”Former Wisconsin Supreme Court Justice Michael Gableman was hired by Republican Assembly Speaker Robin Vos in June 2021 to investigate Donald Trump’s loss in Wisconsin. Vos hired Gableman under …