Bump github.com/spf13/viper from 1.11.0 to 1.15.0

Bumps [github.com/spf13/viper](https://github.com/spf13/viper) from 1.11.0 to 1.15.0.
- [Release notes](https://github.com/spf13/viper/releases)
- [Commits](spf13/viper@v1.11.0...v1.15.0)

---
updated-dependencies:
- dependency-name: github.com/spf13/viper
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

go.mod

@@ -6,6 +6,6 @@ require (
 	github.com/felixge/httpsnoop v1.0.3
 	github.com/google/uuid v1.3.0
 	github.com/gorilla/mux v1.8.0
-	github.com/spf13/viper v1.11.0
+	github.com/spf13/viper v1.15.0
 	go.uber.org/zap v1.21.0
 )