According to the NEP 29 schedule Python 3.7 should have been dropped on Dec 26, 2021. PyTorch adopted this depreciation policy in #74203, and with PyTorch 1.12 released (which still supports Python 3.7), this seems like a good moment to drop Python 3.7 and make the minimum required Python version 3.8, in preparation of PyTorch 1.13.