Bump github.com/gorilla/mux from 1.8.0 to 1.8.1

Bumps [github.com/gorilla/mux](https://github.com/gorilla/mux) from 1.8.0 to 1.8.1.
- [Release notes](https://github.com/gorilla/mux/releases)
- [Commits](https://github.com/gorilla/mux/compare/v1.8.0...v1.8.1)

---
updated-dependencies:
- dependency-name: github.com/gorilla/mux
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

go.mod

@@ -44,7 +44,7 @@ require (
 	github.com/google/uuid v1.4.0
 	github.com/google/wire v0.5.0 // indirect
 	github.com/googleapis/gax-go/v2 v2.12.0 // indirect
-	github.com/gorilla/mux v1.8.0
+	github.com/gorilla/mux v1.8.1
 	github.com/hailocab/go-hostpool v0.0.0-20160125115350-e80d13ce29ed // indirect
 	github.com/hashicorp/errwrap v1.1.0 // indirect
 	github.com/hashicorp/go-multierror v1.1.1 // indirect