feat!: Drop Rails 6.0 EOL #1854

Job	Run time
action_pack / ubuntu-latest	1m 29s
action_view / ubuntu-latest	1m 20s
active_job / ubuntu-latest	2m 48s
active_model_serializers / ubuntu-latest	40s
active_record / ubuntu-latest	1m 5s
active_support / ubuntu-latest	1m 45s
all / ubuntu-latest	2m 19s
aws_sdk / ubuntu-latest	6m 58s
base / ubuntu-latest	1m 31s
concurrent_ruby / ubuntu-latest	2m 29s
delayed_job / ubuntu-latest	45s
ethon / ubuntu-latest	2m 55s
excon / ubuntu-latest	1m 48s
faraday / ubuntu-latest	3m 20s
grape / ubuntu-latest	6m 1s
graphql / ubuntu-latest	1m 19s
gruf / ubuntu-latest	58s
http / ubuntu-latest	1m 44s
http_client / ubuntu-latest	39s
koala / ubuntu-latest	51s
lmdb / ubuntu-latest	1m 13s
net_http / ubuntu-latest	1m 45s
rack / ubuntu-latest	1m 22s
rails / ubuntu-latest	1m 59s
restclient / ubuntu-latest	2m 39s
rspec / ubuntu-latest	1m 34s
sinatra / ubuntu-latest	3m 32s
	56m 48s

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