Bump github.com/stretchr/testify from 1.4.0 to 1.5.1 (#344)

Bumps [github.com/stretchr/testify](https://github.com/stretchr/testify) from 1.4.0 to 1.5.1.
- [Release notes](https://github.com/stretchr/testify/releases)
- [Commits](https://github.com/stretchr/testify/compare/v1.4.0...v1.5.1)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

go.mod

@@ -20,7 +20,7 @@ require (
 	github.com/newrelic/go-agent v2.16.3+incompatible
 	github.com/prometheus/client_golang v0.9.4
 	github.com/sirupsen/logrus v1.4.2
-	github.com/stretchr/testify v1.4.0
+	github.com/stretchr/testify v1.5.1
 	golang.org/x/image v0.0.0-20190802002840-cff245a6509b
 	golang.org/x/net v0.0.0-20191209160850-c0dbc17a3553
 	golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e

go.sum

@@ -264,6 +264,8 @@ github.com/stretchr/testify v1.3.0 h1:TivCn/peBQ7UY8ooIcPgZFpTNSz0Q2U6UrFlUfqbe0
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
+github.com/stretchr/testify v1.5.1 h1:nOGnQDM7FYENwehXlg/kFVnos3rEvtKTjRvOWSzb6H4=
+github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
 github.com/ugorji/go v1.1.4/go.mod h1:uQMGLiO92mf5W77hV/PUCpI3pbzQx3CRekS0kk+RGrc=
 github.com/ugorji/go v1.1.7/go.mod h1:kZn38zHttfInRq0xu/PH0az30d+z6vm202qpg1oXVMw=
 github.com/ugorji/go/codec v0.0.0-20181204163529-d75b2dcb6bc8/go.mod h1:VFNgLljTbGfSG7qAOspJ7OScBnGdDN/yBr0sguwnwf0=