revert guava version; hold for cassandra 3.6 compatibility
revert guava version; hold for cassandra 3.6 compatibility

rrenomeron/cas,tduehr/cas,rrenomeron/cas,robertoschwald/cas,frett/cas,GIP-RECIA/cas,rrenomeron/cas,frett/cas,robertoschwald/cas,tduehr/cas,frett/cas,GIP-RECIA/cas,tduehr/cas,GIP-RECIA/cas,robertoschwald/cas,GIP-RECIA/cas,rrenomeron/cas,robertoschwald/cas,GIP-RECIA/cas,rrenomeron/cas,frett/cas,tduehr/cas