clhep: Add 2.3.1.0 as --devel
clhep: Add 2.3.1.0 as --devel

Geant4 devel version needs latest CLHEP, so add as a devel spec.

SuperNEMO-DBD/homebrew-cadfael,xgarrido/homebrew-cadfael,xgarrido/homebrew-cadfael,SuperNEMO-DBD/homebrew-cadfael