Update nmh jpp version to 12.1.2

MONA has been updated to work with JPP v12.1.2 (the KM3NeT-dataformat IO library), and ROOT6.18.04 The MONA CI build fails because it calls the old version of Jpp, v11.0.0-rc8. https://git.km3net.de/common/analysis/MONA/-/jobs/54079 I think this commit is enough to make the CI work properly, because I believe the ROOT version is not of much concern for MONA, only the paths and libs for JPP are needed.