ST. LOUIS — Build-A-Bear Workshop is demanding a jury trial after being served a lawsuit claiming the St. Louis toy manufacturer’s latest plush line, Skoosherz, is too similar to stuffed toy brand Squishmallows. Last month, Squishmallows’ parent company, California-based Kelly Toys Holdings and its affiliated companies, sued Build-A-Bear and other plush toy retailers over alleged infringement of its trade dress rights, which protect a product’s appearance, shape, labeling, color and design. Build-A-Bear filed a responding lawsuit Monday, asking the court to declare that Squishmallows’ trade dr…