chore(deps): update module cenkalti/backoff to v4

go.mod

@@ -8,7 +8,8 @@ require (
 	github.com/ajg/form v1.5.1 // indirect
 	github.com/aws/aws-lambda-go v1.11.1
 	github.com/aws/aws-sdk-go v1.28.5
-	github.com/cenkalti/backoff v2.2.0+incompatible
+	github.com/cenkalti/backoff v2.2.1+incompatible
+	github.com/cenkalti/backoff/v4 v4.0.0
 	github.com/certifi/gocertifi v0.0.0-20190506164543-d2eda7129713 // indirect
 	github.com/docker/distribution v2.7.1+incompatible // indirect
 	github.com/docker/docker v1.13.1 // indirect

go.sum

@@ -29,6 +29,8 @@ github.com/beorn7/perks v1.0.0/go.mod h1:KWe93zE9D1o94FZ5RNwFwVgaQK1VOXiVxmqh+Ce
 github.com/bombsimon/wsl v1.2.1/go.mod h1:43lEF/i0kpXbLCeDXL9LMT8c92HyBywXb0AsgMHYngM=
 github.com/cenkalti/backoff v2.2.0+incompatible h1:8qVbEY6GLhoLlLi1Ac2ZkVhedNwlhQXc39qivKp9+GI=
 github.com/cenkalti/backoff v2.2.0+incompatible/go.mod h1:b6Nc7NRH5C4aCISLry0tLnTjcuTEvoiqcWDdsU0sOGM=
+github.com/cenkalti/backoff v2.2.1+incompatible/go.mod h1:90ReRw6GdpyfrHakVjL/QHaoyV4aDUVVkXQJJJ3NXXM=
+github.com/cenkalti/backoff/v4 v4.0.0/go.mod h1:eEew/i+1Q6OrCDZh3WiXYv3+nJwBASZ8Bog/87DQnVg=
 github.com/certifi/gocertifi v0.0.0-20190506164543-d2eda7129713 h1:UNOqI3EKhvbqV8f1Vm3NIwkrhq388sGCeAH2Op7w0rc=
 github.com/certifi/gocertifi v0.0.0-20190506164543-d2eda7129713/go.mod h1:GJKEexRPVJrBSOjoqN5VNOIKJ5Q3RViH6eu3puDRwx4=
 github.com/cespare/xxhash v1.1.0/go.mod h1:XrSqR1VqqWfGrhpAt58auRo0WTKS1nRRg3ghfAqPWnc=