dockerfile: upgrade to terraform v0.6.16 (#1533)
dockerfile: upgrade to terraform v0.6.16 (#1533)

[skip ci]
CiscoCloud/microservices-infrastructure,bitium/mantl,sehqlr/mantl,phnmnl/mantl,CiscoCloud/mantl,datascienceinc/mantl,phnmnl/mantl,CiscoCloud/microservices-infrastructure,CiscoCloud/mantl,bitium/mantl,KaGeN101/mantl,mantl/mantl,sehqlr/mantl,mantl/mantl,datascienceinc/mantl,KaGeN101/mantl