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

go.mod

@@ -20,7 +20,7 @@ require (
 	github.com/lunixbochs/struc v0.0.0-20200707160740-784aaebc1d40
 	github.com/miscreant/miscreant.go v0.0.0-20200214223636-26d376326b75
 	github.com/openzipkin/zipkin-go v0.2.5
-	github.com/prometheus/client_golang v1.11.0
+	github.com/prometheus/client_golang v1.12.1
 	github.com/russross/blackfriday/v2 v2.1.0
 	github.com/theckman/go-flock v0.8.1
 	go.opencensus.io v0.23.0