Fix an eslint warning (#12426)

app/javascript/mastodon/features/compose/components/poll_form.js

@@ -144,7 +144,7 @@ class PollForm extends ImmutablePureComponent {
         <div className='poll__footer'>
           <button disabled={options.size >= 4} className='button button-secondary' onClick={this.handleAddOption}><Icon id='plus' /> <FormattedMessage {...messages.add_option} /></button>
 
-          <select value={expiresIn} onChange={this.handleSelectDuration}>
+          <select value={expiresIn} onBlur={this.handleSelectDuration}>
             <option value={300}>{intl.formatMessage(messages.minutes, { number: 5 })}</option>
             <option value={1800}>{intl.formatMessage(messages.minutes, { number: 30 })}</option>
             <option value={3600}>{intl.formatMessage(messages.hours, { number: 1 })}</option>