chore(deps): update dependency go to v1.21.6

go.mod

@@ -1,12 +1,18 @@
 module smtp-proxy-for-notify
 
-go 1.21.5
+go 1.21.6
+
+require (
+	github.com/DusanKasan/parsemail v1.2.0
+	github.com/emersion/go-smtp v0.19.0
+	github.com/rs/zerolog v1.31.0
+	github.com/spf13/viper v1.18.1
+	github.com/stretchr/testify v1.8.4
+)
 
 require (
-	github.com/DusanKasan/parsemail v1.2.0 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
 	github.com/emersion/go-sasl v0.0.0-20200509203442-7bfe0ed36a21 // indirect
-	github.com/emersion/go-smtp v0.19.0 // indirect
 	github.com/fsnotify/fsnotify v1.7.0 // indirect
 	github.com/hashicorp/hcl v1.0.0 // indirect
 	github.com/magiconair/properties v1.8.7 // indirect
@@ -15,16 +21,13 @@ require (
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
 	github.com/pelletier/go-toml/v2 v2.1.0 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
-	github.com/rs/zerolog v1.31.0 // indirect
 	github.com/sagikazarmark/locafero v0.4.0 // indirect
 	github.com/sagikazarmark/slog-shim v0.1.0 // indirect
 	github.com/sourcegraph/conc v0.3.0 // indirect
 	github.com/spf13/afero v1.11.0 // indirect
 	github.com/spf13/cast v1.6.0 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
-	github.com/spf13/viper v1.18.1 // indirect
 	github.com/stretchr/objx v0.5.0 // indirect
-	github.com/stretchr/testify v1.8.4 // indirect
 	github.com/subosito/gotenv v1.6.0 // indirect
 	go.uber.org/atomic v1.9.0 // indirect
 	go.uber.org/multierr v1.9.0 // indirect