Chore(deps): Bump github.com/centrifugal/centrifuge (#31206)

Bumps [github.com/centrifugal/centrifuge](https://github.com/centrifugal/centrifuge) from 0.13.0 to 0.15.0.
- [Release notes](https://github.com/centrifugal/centrifuge/releases)
- [Changelog](https://github.com/centrifugal/centrifuge/blob/master/changelog.md)
- [Commits](https://github.com/centrifugal/centrifuge/compare/v0.13.0...v0.15.0)

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

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

go.mod

@@ -18,7 +18,7 @@ require (
 	github.com/beevik/etree v1.1.0
 	github.com/benbjohnson/clock v0.0.0-20161215174838-7dc76406b6d3
 	github.com/bradfitz/gomemcache v0.0.0-20190913173617-a41fca850d0b
-	github.com/centrifugal/centrifuge v0.13.0
+	github.com/centrifugal/centrifuge v0.15.0
 	github.com/cortexproject/cortex v1.4.1-0.20201022071705-85942c5703cf
 	github.com/crewjam/saml v0.4.6-0.20201227203850-bca570abb2ce
 	github.com/davecgh/go-spew v1.1.1
@@ -67,7 +67,6 @@ require (
 	github.com/prometheus/client_golang v1.9.0
 	github.com/prometheus/client_model v0.2.0
 	github.com/prometheus/common v0.18.0
-	github.com/quasilyte/go-ruleguard/dsl/fluent v0.0.0-20201222093424-5d7e62a465d3 // indirect
 	github.com/robfig/cron v0.0.0-20180505203441-b41be1df6967
 	github.com/robfig/cron/v3 v3.0.1
 	github.com/russellhaering/goxmldsig v1.1.0