Bump github.com/urfave/cli from 1.20.0 to 1.21.0

Bumps [github.com/urfave/cli](https://github.com/urfave/cli) from 1.20.0 to 1.21.0.
- [Release notes](https://github.com/urfave/cli/releases)
- [Changelog](https://github.com/urfave/cli/blob/master/CHANGELOG.md)
- [Commits](urfave/cli@v1.20.0...v1.21.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

go.mod

@@ -5,5 +5,5 @@ go 1.12
 require (
 	github.com/aws/aws-sdk-go v1.21.7
 	github.com/sirupsen/logrus v1.4.2
-	github.com/urfave/cli v1.20.0
+	github.com/urfave/cli v1.21.0
 )

go.sum

@@ -1,3 +1,4 @@
+github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/aws/aws-sdk-go v1.19.38 h1:WKjobgPO4Ua1ww2NJJl2/zQNreUZxvqmEzwMlRjjm9g=
 github.com/aws/aws-sdk-go v1.19.38/go.mod h1:KmX6BPdI08NWTb3/sm4ZGu5ShLoqVDhKgpiN924inxo=
 github.com/aws/aws-sdk-go v1.20.13 h1:Ojyd/HWs30K03id7hpFN/wMVigk3PWvkQXhJgKZjfzs=
@@ -18,5 +19,9 @@ github.com/stretchr/objx v0.1.1/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/urfave/cli v1.20.0 h1:fDqGv3UG/4jbVl/QkFwEdddtEDjh/5Ov6X+0B/3bPaw=
 github.com/urfave/cli v1.20.0/go.mod h1:70zkFmudgCuE/ngEzBv17Jvp/497gISqfk5gWijbERA=
+github.com/urfave/cli v1.21.0 h1:wYSSj06510qPIzGSua9ZqsncMmWE3Zr55KBERygyrxE=
+github.com/urfave/cli v1.21.0/go.mod h1:lxDj6qX9Q6lWQxIrbrT0nwecwUtRnhVZAJjJZrVUZZQ=
 golang.org/x/sys v0.0.0-20190422165155-953cdadca894 h1:Cz4ceDQGXuKRnVBDTS23GTn/pU5OE2C0WrNTOYK1Uuc=
 golang.org/x/sys v0.0.0-20190422165155-953cdadca894/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=