UpdateIndicator: Fix a11y lints

Summary: Adding a role and tabIndex because it's clickable.

Reviewed By: mweststrate

Differential Revision: D20814436

fbshipit-source-id: 2d5acc06363df0cce1c24df7e77b1a6eaa98ab63

desktop/app/src/chrome/UpdateIndicator.tsx

@@ -74,7 +74,10 @@ export default class UpdateIndicator extends React.PureComponent<Props, State> {
 
     const container = (
       <Container>
-        <span onClick={() => shell.openExternal(result.url)}>
+        <span
+          onClick={() => shell.openExternal(result.url)}
+          role="button"
+          tabIndex={0}>
           <Glyph
             color={getSeverityColor(this.props.launcherMsg.severity)}
             name="caution-triangle"