add model for datetime range key spec
add model for datetime range key spec

philipmw/Dynamoid,cavi21/Dynamoid,dnswus/Dynamoid,cavi21/Dynamoid,jlsookiki/Dynamoid,HANDLL/Dynamoid,Dynamoid/Dynamoid,Dynamoid/Dynamoid,philipmw/Dynamoid,BilalBudhani/Dynamoid,BilalBudhani/Dynamoid,dnswus/Dynamoid