Some tweaks are necessary to work on LRZ, readme is outdated,

I am trying to setup ICON-NWP-PSP on the LRZ cluster, but many tweaks were necessary to build ICON. I will take a note here for some help to fix the issues.

1. we should create a new yml file in conf rather than putting everything minimal.yml
2. When compiling on LRZ, use we should use the login node the computing node of LRZ does not have general commands like git.
3. we need to ask a grant to access the dkrz-mirror group in the LRZ gitlab.
4. change the source repository of probtest coded in ~/spack_repo/packages/icon-nwp/package.py to https://github.com/MeteoSwiss/probtest. This might be specific when using the mirrored repositories in gitlab.lrz.de, but I am not sure.
5. Spack compilation seems successfully building ICON, but that cannot find the compiled package with ^openmpi/amct7nx option. Without this option, spack can find the compiled icon.
6. BUILD_PYTHON_ENVIRONMENT job fails with the error in installing cartopy,

fatal error: 'geos_c.h' file not found
  #include "geos_c.h"
           ^~~~~~~~~~

Further points will be added