add starpu dependency in pkg-config

cmake_modules/GenPkgConfig.cmake

@@ -88,9 +88,9 @@ macro(generate_pkgconfig_file)
     if(PASTIX_WITH_STARPU)
       list(APPEND PASTIX_PKGCONFIG_LIBS pastix_starpu)
       if ( PASTIX_WITH_MPI )
-        list(APPEND PASTIX_PKGCONFIG_REQUIRED_PRIVATE libstarpumpi)
+        list(APPEND PASTIX_PKGCONFIG_REQUIRED libstarpumpi)
       else()
-        list(APPEND PASTIX_PKGCONFIG_REQUIRED_PRIVATE libstarpu)
+        list(APPEND PASTIX_PKGCONFIG_REQUIRED libstarpu)
       endif()
     endif()