Fix pyomo version at ~=5.1
Fix pyomo version at ~=5.1

nismod/smif,tomalrussell/smif,tomalrussell/smif,nismod/smif,willu47/smif,nismod/smif,nismod/smif,tomalrussell/smif,willu47/smif,willu47/smif,willu47/smif,tomalrussell/smif