chore(deps): bump github.com/operator-framework/operator-sdk

Bumps [github.com/operator-framework/operator-sdk](https://github.com/operator-framework/operator-sdk) from 0.17.0 to 0.18.0.
- [Release notes](https://github.com/operator-framework/operator-sdk/releases)
- [Changelog](https://github.com/operator-framework/operator-sdk/blob/master/CHANGELOG.md)
- [Commits](operator-framework/operator-sdk@v0.17.0...v0.18.0)

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

go.mod

@@ -7,12 +7,10 @@ require (
 	github.com/golang/protobuf v1.3.2 // indirect
 	github.com/onsi/ginkgo v1.10.1 // indirect
 	github.com/onsi/gomega v1.7.0 // indirect
-	github.com/operator-framework/operator-sdk v0.17.0
+	github.com/operator-framework/operator-sdk v0.18.0
 	github.com/sirupsen/logrus v1.6.0
 	github.com/spf13/pflag v1.0.5
-	github.com/stretchr/testify v1.4.0 // indirect
 	golang.org/x/crypto v0.0.0-20190909091759-094676da4a83 // indirect
-	golang.org/x/net v0.0.0-20190909003024-a7b16738d86b // indirect
 	golang.org/x/sys v0.0.0-20190909082730-f460065e899a // indirect
 	golang.org/x/tools v0.0.0-20190910044552-dd2b5c81c578 // indirect
 	gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 // indirect