chore(deps): bump github.com/spf13/viper from 1.7.1 to 1.8.1

Bumps [github.com/spf13/viper](https://github.com/spf13/viper) from 1.7.1 to 1.8.1.
- [Release notes](https://github.com/spf13/viper/releases)
- [Commits](spf13/viper@v1.7.1...v1.8.1)

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

Signed-off-by: dependabot[bot] <[email protected]>

go.mod

@@ -8,7 +8,6 @@ require (
 	github.com/Netflix/go-expect v0.0.0-20200312175327-da48e75238e2
 	github.com/briandowns/spinner v1.12.0
 	github.com/fatih/color v1.12.0
-	github.com/fsnotify/fsnotify v1.4.9 // indirect
 	github.com/google/btree v1.0.1 // indirect
 	github.com/hinshun/vt10x v0.0.0-20180809195222-d55458df857c
 	github.com/hokaccha/go-prettyjson v0.0.0-20190818114111-108c894c2c0e
@@ -18,20 +17,14 @@ require (
 	github.com/mitchellh/go-homedir v1.1.0
 	github.com/mitchellh/mapstructure v1.4.1
 	github.com/olekukonko/tablewriter v0.0.5
-	github.com/pelletier/go-toml v1.6.0 // indirect
 	github.com/peterbourgon/diskv/v3 v3.0.0
 	github.com/pkg/errors v0.9.1
-	github.com/spf13/afero v1.2.2 // indirect
-	github.com/spf13/cast v1.3.1 // indirect
 	github.com/spf13/cobra v1.1.3
-	github.com/spf13/jwalterweatherman v1.1.0 // indirect
 	github.com/spf13/pflag v1.0.5
-	github.com/spf13/viper v1.7.1
+	github.com/spf13/viper v1.8.1
 	github.com/stretchr/testify v1.7.0
 	go.uber.org/zap v1.18.1
 	golang.org/x/crypto v0.0.0-20201124201722-c8d3bf9c5392
-	golang.org/x/tools v0.1.2 // indirect
-	gopkg.in/ini.v1 v1.55.0 // indirect
 	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b
 )