build(deps): bump github.com/stretchr/testify from 1.4.0 to 1.5.1

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>

go.mod

@@ -33,7 +33,7 @@ require (
 	github.com/multiformats/go-multiaddr-dns v0.2.0
 	github.com/multiformats/go-multiaddr-net v0.1.4
 	github.com/multiformats/go-multistream v0.1.1
-	github.com/stretchr/testify v1.4.0
+	github.com/stretchr/testify v1.5.1
 	github.com/whyrusleeping/mdns v0.0.0-20190826153040-b9b60ed33aa9
 )
 

go.sum

@@ -383,11 +383,14 @@ github.com/spf13/pflag v1.0.3/go.mod h1:DYY7MBk1bdzusC3SYhjObp+wFpr4gzcvqqNjLnIn
 github.com/spf13/viper v1.3.2/go.mod h1:ZiWeW+zYFKm7srdB9IoDzzZXaJaI5eL9QjNiN/DMA2s=
 github.com/src-d/envconfig v1.0.0/go.mod h1:Q9YQZ7BKITldTBnoxsE5gOeB5y66RyPXeue/R4aaNBc=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.1.1 h1:2vfRuCMp5sSVIDSqO8oNnWJq7mPa6KVP3iPIwFBuy8A=
 github.com/stretchr/objx v0.1.1/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 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/syndtr/goleveldb v1.0.0/go.mod h1:ZVVdQEZoIme9iO1Ch2Jdy24qqXrMMOU6lpPAyBWyWuQ=
 github.com/ugorji/go/codec v0.0.0-20181204163529-d75b2dcb6bc8/go.mod h1:VFNgLljTbGfSG7qAOspJ7OScBnGdDN/yBr0sguwnwf0=
 github.com/whyrusleeping/go-keyspace v0.0.0-20160322163242-5b898ac5add1/go.mod h1:8UvriyWtv5Q5EOgjHaSseUEdkQfvwFv1I/In/O2M9gc=