fix(deps): update module github.com/spf13/viper to v1.8.0 (#180)

Co-authored-by: Renovate Bot <bot@renovateapp.com>

go.mod

@@ -12,24 +12,20 @@ require (
 	github.com/gorilla/mux v1.8.0
 	github.com/huandu/xstrings v1.3.2 // indirect
 	github.com/kr/pretty v0.2.0 // indirect
-	github.com/magiconair/properties v1.8.4 // indirect
 	github.com/mitchellh/copystructure v1.1.1 // indirect
 	github.com/mitchellh/mapstructure v1.4.1 // indirect
 	github.com/mohae/deepcopy v0.0.0-20170929034955-c48cc78d4826
-	github.com/pelletier/go-toml v1.8.1 // indirect
 	github.com/prometheus/client_golang v1.10.0
 	github.com/robfig/cron/v3 v3.0.1
 	github.com/rs/xid v1.3.0
 	github.com/rs/zerolog v1.23.0
 	github.com/slack-go/slack v0.8.2
-	github.com/spf13/afero v1.5.1 // indirect
 	github.com/spf13/jwalterweatherman v1.1.0 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
-	github.com/spf13/viper v1.7.1
+	github.com/spf13/viper v1.8.0
 	github.com/technoweenie/multipartstreamer v1.0.1 // indirect
 	golang.org/x/crypto v0.0.0-20210220033148-5ea612d1eb83 // indirect
 	golang.org/x/text v0.3.5 // indirect
-	google.golang.org/protobuf v1.25.0 // indirect
 	gopkg.in/ini.v1 v1.62.0 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 )