[Glitch] Run eslint --fix

I don't like it changing files this way, but it's basically what
c49213f0ea and a few others did.

app/javascript/flavours/glitch/components/column_back_button.js

@@ -26,7 +26,7 @@ export default class ColumnBackButton extends React.PureComponent {
     } else {
       this.context.router.history.push('/');
     }
-  }
+  };
 
   render () {
     const { multiColumn } = this.props;