vendor: update github.com/spf13/cobra to master

vendor/github.com/spf13/cobra/args.go

@@ -78,6 +78,18 @@ func ExactArgs(n int) PositionalArgs {
 	}
 }
 
+// ExactValidArgs returns an error if
+// there are not exactly N positional args OR
+// there are any positional args that are not in the `ValidArgs` field of `Command`
+func ExactValidArgs(n int) PositionalArgs {
+	return func(cmd *Command, args []string) error {
+		if err := ExactArgs(n)(cmd, args); err != nil {
+			return err
+		}
+		return OnlyValidArgs(cmd, args)
+	}
+}
+
 // RangeArgs returns an error if the number of args is not within the expected range.
 func RangeArgs(min int, max int) PositionalArgs {
 	return func(cmd *Command, args []string) error {