message: reformulates libCEED version requirement.
diff: #include <ceed/hash.h>
  #include <ceed/backend.h> // for CeedOperatorField
  #if !CEED_VERSION_GE(0,10,0)
  -#error MFEM requires a libCEED version superior to 0.10.0
  +#error MFEM requires a libCEED version >= 0.10.0
  #endif
  #endif
  #include <tuple>
  