GeoModel version bumped to 5.3.0

cmake/GeoModel-version.cmake

 # Set up the version of GeoModel as a cache variable, so that other
 # sub-projects could use this value.
-set( GeoModel_VERSION "5.1.0" CACHE STRING
+set( GeoModel_VERSION "5.3.0" CACHE STRING
     "Version of the GeoModel project" )