Bump github.com/stretchr/testify from 1.5.0 to 1.5.1

Bumps [github.com/stretchr/testify](https://github.com/stretchr/testify) from 1.5.0 to 1.5.1.
- [Release notes](https://github.com/stretchr/testify/releases)
- [Commits](stretchr/testify@v1.5.0...v1.5.1)

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

Author: dependabot-preview[bot]

go.mod

@@ -3,6 +3,6 @@ module github.com/oschwald/maxminddb-golang
 go 1.9
 
 require (
-	github.com/stretchr/testify v1.5.0
+	github.com/stretchr/testify v1.5.1
 	golang.org/x/sys v0.0.0-20191224085550-c709ea063b76
 )

go.sum

@@ -8,6 +8,8 @@ github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJy
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.5.0 h1:DMOzIV76tmoDNE9pX6RSN0aDtCYeCg5VueieJaAo1uw=
 github.com/stretchr/testify v1.5.0/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
+github.com/stretchr/testify v1.5.1 h1:nOGnQDM7FYENwehXlg/kFVnos3rEvtKTjRvOWSzb6H4=
+github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
 golang.org/x/sys v0.0.0-20191224085550-c709ea063b76 h1:Dho5nD6R3PcW2SH1or8vS0dszDaXRxIw55lBX7XiE5g=
 golang.org/x/sys v0.0.0-20191224085550-c709ea063b76/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=