Add tootctl --version (mastodon#9835)

Author: Gargron

lib/cli.rb

@@ -7,6 +7,7 @@
 require_relative 'mastodon/feeds_cli'
 require_relative 'mastodon/settings_cli'
 require_relative 'mastodon/domains_cli'
+require_relative 'mastodon/version'
 
 module Mastodon
   class CLI < Thor
@@ -31,5 +32,12 @@ def self.exit_on_failure?
 
     desc 'domains SUBCOMMAND ...ARGS', 'Manage account domains'
     subcommand 'domains', Mastodon::DomainsCLI
+
+    map %w(--version -v) => :version
+
+    desc 'version', 'Show version'
+    def version
+      say(Mastodon::Version.to_s)
+    end
   end
 end