Bump github.com/gorilla/mux from 1.7.4 to 1.8.0 (#396)

Bumps [github.com/gorilla/mux](https://github.com/gorilla/mux) from 1.7.4 to 1.8.0.
- [Release notes](https://github.com/gorilla/mux/releases)
- [Commits](gorilla/mux@v1.7.4...v1.8.0)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

go.mod

@@ -34,7 +34,7 @@ require (
 	github.com/google/uuid v1.1.1
 	github.com/googleapis/gnostic v0.3.1
 	github.com/gophercloud/gophercloud v0.0.0-20190516165734-b3a23cc94cc5
-	github.com/gorilla/mux v1.7.4
+	github.com/gorilla/mux v1.8.0
 	github.com/gregjones/httpcache v0.0.0-20190212212710-3befbb6ad0cc
 	github.com/grpc-ecosystem/grpc-gateway v1.14.7
 	github.com/hashicorp/golang-lru v0.5.4

go.sum

@@ -354,6 +354,8 @@ github.com/gorilla/mux v1.7.2/go.mod h1:1lud6UwP+6orDFRuTfBEV8e9/aOM/c4fVVCaMa2z
 github.com/gorilla/mux v1.7.3/go.mod h1:1lud6UwP+6orDFRuTfBEV8e9/aOM/c4fVVCaMa2zaAs=
 github.com/gorilla/mux v1.7.4 h1:VuZ8uybHlWmqV03+zRzdwKL4tUnIp1MAQtp1mIFE1bc=
 github.com/gorilla/mux v1.7.4/go.mod h1:DVbg23sWSpFRCP0SfiEN6jmj59UnW/n46BH5rLB71So=
+github.com/gorilla/mux v1.8.0 h1:i40aqfkR1h2SlN9hojwV5ZA91wcXFOvkdNIeFDP5koI=
+github.com/gorilla/mux v1.8.0/go.mod h1:DVbg23sWSpFRCP0SfiEN6jmj59UnW/n46BH5rLB71So=
 github.com/gorilla/websocket v0.0.0-20170926233335-4201258b820c/go.mod h1:E7qHFY5m1UJ88s3WnNqhKjPHQ0heANvMoAMk2YaljkQ=
 github.com/gorilla/websocket v1.4.0/go.mod h1:E7qHFY5m1UJ88s3WnNqhKjPHQ0heANvMoAMk2YaljkQ=
 github.com/gregjones/httpcache v0.0.0-20190212212710-3befbb6ad0cc h1:f8eY6cV/x1x+HLjOp4r72s/31/V2aTUtg5oKRRPf8/Q=