go.mod: update to make dependabot leave me alone.

Signed-off-by: David Anderson <dave@natulte.net>

go.mod

@@ -1,21 +1,13 @@
 module go.universe.tf/netboot
 
 require (
-	github.com/google/go-cmp v0.2.0
-	github.com/pelletier/go-toml v1.6.0 // indirect
-	github.com/spf13/afero v1.2.2 // indirect
-	github.com/spf13/cast v1.3.1 // indirect
-	github.com/spf13/cobra v0.0.5
-	github.com/spf13/jwalterweatherman v1.1.0 // indirect
-	github.com/spf13/pflag v1.0.5 // indirect
-	github.com/spf13/viper v1.6.2
-	github.com/stretchr/testify v1.3.0 // indirect
-	golang.org/x/crypto v0.0.0-20200117160349-530e935923ad
-	golang.org/x/net v0.0.0-20200114155413-6afb5195e5aa
-	golang.org/x/sys v0.0.0-20200124204421-9fbb57f87de9 // indirect
-	golang.org/x/text v0.3.2 // indirect
-	gopkg.in/ini.v1 v1.51.1 // indirect
-	gopkg.in/yaml.v2 v2.2.8 // indirect
+	github.com/google/go-cmp v0.5.9
+	github.com/inconshreveable/mousetrap v1.1.0 // indirect
+	github.com/spf13/afero v1.9.4 // indirect
+	github.com/spf13/cobra v1.6.1
+	github.com/spf13/viper v1.15.0
+	golang.org/x/crypto v0.6.0
+	golang.org/x/net v0.7.0
 )
 
 go 1.13