Fix content of .data_packages_found.txt for packages with version constraints
in !207 (merged) I forgot that the global property DATA_PACKAGES_FOUND
contains strings like <name>:<version>
(instead of just <name>
) if the data package is requested with a version constraint (see https://gitlab.cern.ch/lhcb/LHCb/-/blob/9082f87d0c08faa6a24d64f9cfce10db41f7fa11/cmake/FindDataPackage.cmake#L162).