Drop Python 3.6 support #468

Job	Run time
Test aip-encrypt on Firefox	23m 43s
Test aip-encrypt on Chrome	25m 58s
Test aip-encrypt-mirror on Firefox	21m 4s
Test aip-encrypt-mirror on Chrome	16m 8s
Test black-box on Chrome	40m 31s
Test icc on Firefox	21m 20s
Test icc on Chrome	16m 29s
Test ipc preservation on Firefox	40m 10s
Test ipc preservation on Chrome	36m 21s
Test ipc access on Firefox	35m 32s
Test ipc access on Chrome	36m 24s
Test metadata-xml on Firefox	29m 53s
Test metadata-xml on Chrome	28m 14s
Test tcc on Firefox	21m 43s
Test tcc on Chrome	21m 11s
Test tpc on Firefox	24m 5s
Test tpc on Chrome	17m 8s
Test uuids-dirs on Firefox	16m 21s
Test uuids-dirs on Chrome	18m 52s
	8h 11m 7s

Provide feedback