How to install latest version of transformers?

No matter what command I try, I always end up with version 2.1.1 of transformers, where models such as the GPT2 do not accept the input_embeds arguments in the forward pass, which I really need.
How can I install the latest version? I have tried with conda, with pip, I have tried updating but so far I am stuck with 2.1.1

Making a new virtual environment in which I re-installed everything solved my issue but I do not know why… Weird.