Update module github.com/prometheus/client_golang to v1.12.1

Author: renovate-bot

go.mod

@@ -5,7 +5,7 @@ go 1.14
 require (
 	github.com/golang-jwt/jwt v3.2.2+incompatible
 	github.com/gorilla/websocket v1.4.2
-	github.com/prometheus/client_golang v1.6.0
+	github.com/prometheus/client_golang v1.12.1
 	github.com/rs/zerolog v1.18.0
 	github.com/sirupsen/logrus v1.8.1
 	github.com/stretchr/testify v1.7.0