It’s the first week of September, which means, cue Seinfeld’s George Costanza, we’re “shifting into soup mode.” Panera Bread is right there with us, rolling out its new fall menu today. The seasonal offerings include the return of two soups: rustic baked potato soup and autumn squash soup. The fast-casual chain is also adding a three-cheese lasagna soup to its menu for the first time. The soup has a ricotta tomato broth with Italian-style sausa…