Draft: Test version which only checks new geometries

Test the new STS geometry sts_v21e_sis18 only within the sis100_setup. This is a first step tow check if the geometry works on all platforms.

external/InstallGeometry.cmake

 set(GEOMETRY_VERSION 6b0ed9654327dfdeccdab4bedc87040d3b4ddcc7)
 
-set(GEOMETRY_SRC_URL "https://git.cbm.gsi.de/CbmSoft/cbmroot_geometry.git")
+set(GEOMETRY_SRC_URL "https://git.cbm.gsi.de/f.uhlig/cbmroot_geometry.git")
 
 download_project_if_needed(PROJECT         Geometry_source
                            GIT_REPOSITORY  ${GEOMETRY_SRC_URL}