Add pyjwt

For a reason I don't understand recently lb-conda default stopped providing the pyjwt library

https://pyjwt.readthedocs.io/en/stable/

which is used by the HLT piquet tools to populate trend plots in MONET. There are ways around this but the simplest would be to add pyjwt as an explicit dependency to the default conda environment. Is there a good reason not to do this?

cc @robbep @cagapopo @rmatev