Bump golang.org/x/mod from 0.5.1 to 0.8.0

Bumps [golang.org/x/mod](https://github.com/golang/mod) from 0.5.1 to 0.8.0.
- [Release notes](https://github.com/golang/mod/releases)
- [Commits](https://github.com/golang/mod/compare/v0.5.1...v0.8.0)

---
updated-dependencies:
- dependency-name: golang.org/x/mod
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

go.mod

@@ -4,6 +4,6 @@ go 1.16
 
 require (
 	github.com/gorilla/mux v1.8.0
-	golang.org/x/mod v0.5.1
+	golang.org/x/mod v0.8.0
 	gopkg.in/yaml.v2 v2.4.0
 )