Add rule to enforce spacing in curly brackets in JSX children

This required an updated in version of eslint-plugin-react to 7.4.0.

src/components/views/elements/AppWarning.js

@@ -6,10 +6,10 @@ const AppWarning = (props) => {
     return (
         <div className='mx_AppPermissionWarning'>
             <div className='mx_AppPermissionWarningImage'>
-                <img src='img/warning.svg' alt={_t('Warning!')}/>
+                <img src='img/warning.svg' alt={_t('Warning!')} />
             </div>
             <div className='mx_AppPermissionWarningText'>
-                <span className='mx_AppPermissionWarningTextLabel'>{props.errorMsg}</span>
+                <span className='mx_AppPermissionWarningTextLabel'>{ props.errorMsg }</span>
             </div>
         </div>
     );