chore(deps): bump github.com/prometheus/client_golang (#131)

Bumps [github.com/prometheus/client_golang](https://github.com/prometheus/client_golang) from 1.11.0 to 1.12.0.
- [Release notes](https://github.com/prometheus/client_golang/releases)
- [Changelog](https://github.com/prometheus/client_golang/blob/main/CHANGELOG.md)
- [Commits](prometheus/client_golang@v1.11.0...v1.12.0)

---
updated-dependencies:
- dependency-name: github.com/prometheus/client_golang
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

go.mod

@@ -17,13 +17,12 @@ require (
 	github.com/gorilla/mux v1.8.0
 	github.com/matryer/is v1.4.0
 	github.com/onsi/ginkgo v1.7.0 // indirect
-	github.com/prometheus/client_golang v1.11.0
+	github.com/prometheus/client_golang v1.12.0
 	github.com/vmihailenco/msgpack v4.0.2+incompatible // indirect
 	github.com/wcharczuk/go-chart v2.0.1+incompatible
 	github.com/yuin/gopher-lua v0.0.0-20190514113301-1cd887cd7036 // indirect
 	golang.org/x/image v0.0.0-20200618115811-c13761719519 // indirect
 	golang.org/x/sync v0.0.0-20201207232520-09787c993a3a
-	google.golang.org/appengine v1.6.6 // indirect
 	gopkg.in/h2non/gock.v1 v1.1.2
 	gopkg.in/vmihailenco/msgpack.v2 v2.9.2
 )