Bump github.com/stretchr/testify from 1.8.0 to 1.8.1

Bumps [github.com/stretchr/testify](https://github.com/stretchr/testify) from 1.8.0 to 1.8.1.
- [Release notes](https://github.com/stretchr/testify/releases)
- [Commits](stretchr/testify@v1.8.0...v1.8.1)

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

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

go.mod

@@ -15,7 +15,7 @@ require (
 	github.com/mrz1836/go-sanitize v1.1.5
 	github.com/mrz1836/go-validate v0.2.0
 	github.com/newrelic/go-agent/v3/integrations/nrhttprouter v1.0.1
-	github.com/stretchr/testify v1.8.0
+	github.com/stretchr/testify v1.8.1
 	golang.org/x/net v0.1.0
 )