build(deps): bump github.com/spf13/viper from 1.19.0 to 1.21.0 in /proxy

Bumps [github.com/spf13/viper](https://github.com/spf13/viper) from 1.19.0 to 1.21.0.
- [Release notes](https://github.com/spf13/viper/releases)
- [Commits](https://github.com/spf13/viper/compare/v1.19.0...v1.21.0)

---
updated-dependencies:
- dependency-name: github.com/spf13/viper
  dependency-version: 1.21.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

proxy/go.mod

@@ -1,32 +1,26 @@
 module github.com/xddxdd/bird-lg-go/proxy
 
-go 1.17
+go 1.23.0
 
 require (
 	github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510
 	github.com/gorilla/handlers v1.5.2
 	github.com/magiconair/properties v1.8.10
 	github.com/spf13/pflag v1.0.10
-	github.com/spf13/viper v1.19.0
+	github.com/spf13/viper v1.21.0
 )
 
 require (
 	github.com/felixge/httpsnoop v1.0.4 // indirect
-	github.com/fsnotify/fsnotify v1.7.0 // indirect
-	github.com/hashicorp/hcl v1.0.0 // indirect
-	github.com/mitchellh/mapstructure v1.5.0 // indirect
-	github.com/pelletier/go-toml/v2 v2.2.2 // 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/fsnotify/fsnotify v1.9.0 // indirect
+	github.com/go-viper/mapstructure/v2 v2.4.0 // indirect
+	github.com/pelletier/go-toml/v2 v2.2.4 // indirect
+	github.com/sagikazarmark/locafero v0.11.0 // indirect
+	github.com/sourcegraph/conc v0.3.1-0.20240121214520-5f936abd7ae8 // indirect
+	github.com/spf13/afero v1.15.0 // indirect
+	github.com/spf13/cast v1.10.0 // 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
-	golang.org/x/exp v0.0.0-20230905200255-921286631fa9 // indirect
-	golang.org/x/sys v0.18.0 // indirect
-	golang.org/x/text v0.14.0 // indirect
-	gopkg.in/ini.v1 v1.67.0 // indirect
-	gopkg.in/yaml.v3 v3.0.1 // indirect
+	go.yaml.in/yaml/v3 v3.0.4 // indirect
+	golang.org/x/sys v0.29.0 // indirect
+	golang.org/x/text v0.28.0 // indirect
 )