Michael Schneider Variety Editor at LargeIt’s not quite the “Gravity Falls” reboot/reunion that fans are hoping for, but it’s close: Creator Alex Hirsch will guest star on a Season 2 episode of Disney Channel’s “Amphibia” that pays homage to the animated cult fave.In the “Amphibia” episode titled “Wax Museum,” the show’s family travels to a mysterious roadside oddities museum that looks and feels quite a bit like the Mystery Shack on “Gravity Falls.” Hirsch, who voiced Grunkle Stan on that