Bump github.com/stretchr/testify from 1.8.4 to 1.9.0

Bumps [github.com/stretchr/testify](https://github.com/stretchr/testify) from 1.8.4 to 1.9.0.
- [Release notes](https://github.com/stretchr/testify/releases)
- [Commits](stretchr/testify@v1.8.4...v1.9.0)

---
updated-dependencies:
- dependency-name: github.com/stretchr/testify
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

go.mod

@@ -26,7 +26,7 @@ require (
 	github.com/songgao/water v0.0.0-20200317203138-2b4b6d7c09d8
 	github.com/spf13/cast v1.4.1
 	github.com/spf13/pflag v1.0.5
-	github.com/stretchr/testify v1.8.4
+	github.com/stretchr/testify v1.9.0
 	github.com/vishvananda/netlink v1.2.1-beta.2
 	go.etcd.io/bbolt v1.3.9
 	gopkg.in/ini.v1 v1.67.0