Display Mastodon version in footer of web UI (#8013)

Fix #7846

app/javascript/mastodon/features/getting_started/index.js

@@ -7,7 +7,7 @@ import { connect } from 'react-redux';
 import PropTypes from 'prop-types';
 import ImmutablePropTypes from 'react-immutable-proptypes';
 import ImmutablePureComponent from 'react-immutable-pure-component';
-import { me, invitesEnabled } from '../../initial_state';
+import { me, invitesEnabled, version } from '../../initial_state';
 import { fetchFollowRequests } from '../../actions/accounts';
 import { List as ImmutableList } from 'immutable';
 import { Link } from 'react-router-dom';
@@ -149,7 +149,7 @@ export default class GettingStarted extends ImmutablePureComponent {
             <FormattedMessage
               id='getting_started.open_source_notice'
               defaultMessage='Mastodon is open source software. You can contribute or report issues on GitHub at {github}.'
-              values={{ github: <a href='https://github.com/tootsuite/mastodon' rel='noopener' target='_blank'>tootsuite/mastodon</a> }}
+              values={{ github: <span><a href='https://github.com/tootsuite/mastodon' rel='noopener' target='_blank'>tootsuite/mastodon</a> (v{version})</span> }}
             />
           </p>
         </div>

app/javascript/mastodon/initial_state.js

@@ -12,5 +12,6 @@ export const deleteModal = getMeta('delete_modal');
 export const me = getMeta('me');
 export const searchEnabled = getMeta('search_enabled');
 export const invitesEnabled = getMeta('invites_enabled');
+export const version = getMeta('version');
 
 export default initialState;

app/serializers/initial_state_serializer.rb

@@ -14,6 +14,7 @@ class InitialStateSerializer < ActiveModel::Serializer
       domain: Rails.configuration.x.local_domain,
       admin: object.admin&.id&.to_s,
       search_enabled: Chewy.enabled?,
+      version: Mastodon::Version.to_s,
       invites_enabled: Setting.min_invite_role == 'user',
     }