chore(deps): bump github.com/hashicorp/consul from 1.4.0 to 1.5.1

Bumps [github.com/hashicorp/consul](https://github.com/hashicorp/consul) from 1.4.0 to 1.5.1.
- [Release notes](https://github.com/hashicorp/consul/releases)
- [Changelog](https://github.com/hashicorp/consul/blob/master/CHANGELOG.md)
- [Commits](hashicorp/consul@v1.4.0...v1.5.1)

go.mod

@@ -3,7 +3,7 @@ module github.com/morningconsult/go-elasticsearch-alerts
 require (
  github.com/armon/go-metrics v0.0.0-20180917152333-f0300d1749da // indirect
  github.com/golang/snappy v0.0.0-20180518054509-2e65f85255db // indirect
- github.com/hashicorp/consul v1.4.0
+ github.com/hashicorp/consul v1.5.1
  github.com/hashicorp/go-cleanhttp v0.5.0
  github.com/hashicorp/go-hclog v0.0.0-20190109152822-4783caec6f2e
  github.com/hashicorp/go-immutable-radix v1.0.0 // indirect