Former President Donald Trump elicited mockery on Thursday after he took aim at an Oscar-winning actor he dubbed a “fake” and a “rat.” In fact, Trump quickly saw his attacks boomerang after he slammed George Clooney’s call on President Joe Biden to resign. “Trump’s patently immature rant demonstrates more than a little reluctance to see his 81-year-old opponent exit the race,” quips New Republic writer Edith Olmsted. “Maybe Trump understands that in politics, like in Hollywood, youth is currency, and the 78-year-old is scared that he just can’t compete.” Want more breaking political news? Clic…