Adds information on whether a specific project car read/write zstd compressed files in the project-info.json

This MR does not update the stacks, but changes the data exported to CVMFS by the GitLab CI. No need for the usual validations, this will not trigger a build

It updates the code that is invoked by the CI to generate the file /cvmfs/lhcb.cern.ch/lib/var/lib/softmetadata/projects-info.json, so that the data for a given version of a project becomes:

   "MOORE": {
        "v10r1": {
            "GAUDI": "v21r10p1",
            "LCG": "58e",
            "ROOT": "5.26.00cp1",
            "platforms": [
                "slc4_amd64_gcc34",
                "slc4_ia32_gcc34",
                "x86_64-slc5-gcc43-opt"
            ],
            "read_zstd": false,
            "write_zstd": false
        },

Other changes to be considered in separate MRs:

• The code that maps from LCG version to ROOT version actually has to fetch data from https://lcgpackages.web.cern.ch/lcg/meta/, this should be reviewed in a later MR.
• xrootd version information
• upgrade of python for the CI tests (currently 3.8)

FYI @admorris @cburr @clemenci