build(deps): bump github.com/prometheus/common from 0.7.0 to 0.9.1 (#3622)

Bumps [github.com/prometheus/common](https://github.com/prometheus/common) from 0.7.0 to 0.9.1.
- [Release notes](https://github.com/prometheus/common/releases)
- [Commits](https://github.com/prometheus/common/compare/v0.7.0...v0.9.1)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

go.mod

@@ -31,7 +31,7 @@ require (
 	github.com/philhofer/fwd v1.0.0 // indirect
 	github.com/prometheus/client_golang v1.3.0
 	github.com/prometheus/client_model v0.2.0
-	github.com/prometheus/common v0.7.0
+	github.com/prometheus/common v0.9.1
 	github.com/tinylib/msgp v1.1.0 // indirect
 	github.com/tmc/grpc-websocket-proxy v0.0.0-20190109142713-0ad062ec5ee5 // indirect
 	go.etcd.io/etcd v0.5.0-alpha.5.0.20190917205325-a14579fbfb1a

go.sum

@@ -358,6 +358,8 @@ github.com/prometheus/common v0.4.1/go.mod h1:TNfzLD0ON7rHzMJeJkieUDPYmFC7Snx/y8
 github.com/prometheus/common v0.6.0/go.mod h1:eBmuwkDJBwy6iBfxCBob6t6dR6ENT/y+J+Zk0j9GMYc=
 github.com/prometheus/common v0.7.0 h1:L+1lyG48J1zAQXA3RBX/nG/B3gjlHq0zTt2tlbJLyCY=
 github.com/prometheus/common v0.7.0/go.mod h1:DjGbpBbp5NYNiECxcL/VnbXCCaQpKd3tt26CguLLsqA=
+github.com/prometheus/common v0.9.1 h1:KOMtN28tlbam3/7ZKEYKHhKoJZYYj3gMH4uc62x7X7U=
+github.com/prometheus/common v0.9.1/go.mod h1:yhUN8i9wzaXS3w1O07YhxHEBxD+W35wd8bs7vj7HSQ4=
 github.com/prometheus/procfs v0.0.0-20181005140218-185b4288413d/go.mod h1:c3At6R/oaqEKCNdg8wHV1ftS6bRYblBhIjjI8uT2IGk=
 github.com/prometheus/procfs v0.0.0-20190117184657-bf6a532e95b1/go.mod h1:c3At6R/oaqEKCNdg8wHV1ftS6bRYblBhIjjI8uT2IGk=
 github.com/prometheus/procfs v0.0.2/go.mod h1:TjEm7ze935MbeOT/UhFTIMYKhuLP4wbCsTZCD3I8kEA=