WKWebView reports are always 18.6 #3315

See WebView-CG/CanIWKWebView#7 (comment)
Collector runs will always report 18.6, like in openwebdocs/mdn-bcd-results#1439.

We need to find a different way to say in which version compat data was collected as the information is not available from the UA string anymore, see also https://mastodon.cloud/@karlcow/115152108505379796.