You can prepare the return using the 2019 version of TurboTax Business, but you will not be able to e-file. Rather, you will need to make some manual entries in Forms Mode, print out the return, manually correct the dates on your 1065 and K-1s (at least), and then mail the return.
To avoid overwriting your previously filed return for 2019, ensure that you save that file under a unique file name and copy the file to at least two different media (e.g., an external hard drive or SSD and a USB flash drive).
