Woman with her smartphone poses in front of displayed Duolingo logo in this illustration taken, June 29, 2021. REUTERS/Dado Ruvic/Illustration/File Photo Purchase Licensing Rights, opens new tabAug 6 (Reuters) - Language-learning app Duolingo (DUOL.O), opens new tab raised its annual revenue forecast and beat second-quarter revenue estimates on Wednesday, anticipating broader adoption of its AI-enhanced subscription tier among its global user base.The company's shares rose about 20% in trading a...