build(deps): bump github.com/pkg/errors from 0.8.1 to 0.9.1 (#42)

Bumps [github.com/pkg/errors](https://github.com/pkg/errors) from 0.8.1 to 0.9.1.
- [Release notes](https://github.com/pkg/errors/releases)
- [Commits](https://github.com/pkg/errors/compare/v0.8.1...v0.9.1)

---
updated-dependencies:
- dependency-name: github.com/pkg/errors
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

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

go.mod

@@ -9,7 +9,7 @@ require (
 	github.com/itzg/go-flagsfiller v1.4.2
 	github.com/juju/ratelimit v1.0.1
 	github.com/pires/go-proxyproto v0.6.1
-	github.com/pkg/errors v0.8.1
+	github.com/pkg/errors v0.9.1
 	github.com/sirupsen/logrus v1.4.1
 	github.com/stretchr/testify v1.4.0
 	golang.org/x/text v0.3.2