title: Flutter url_launcher is not launching url in release mode
body: <p>I don't know for some reason <code>url_launcher</code> (<a href="https://pub.dev/packages/url_launcher" rel="noreferrer">https://pub.dev/packages/url_launcher</a>) is not working after downloading app from google playstore. In debug mode it is working the way it should be. But after uploading app on playstore and downloading it from there, url launcher is not launching any url. WHY is that?</p>
  <pre class="lang-dart prettyprint-override"><code>import 'package:url_launcher/url_launcher.dart';
  
   onTap: () {
    launchURL(&quot;https://www.google.com&quot;);
  },
  ..............
    launchURL(String url) async {
      if (await canLaunch(url)) {
        await launch(url);
      } else {
        throw 'Could not launch $url';
      }
    }
  </code></pre>
  <p><strong>pubspec.yaml</strong>
  <code>url_launcher: ^5.7.6</code></p>
  <p>I've also added <code>android.permission.INTERNET</code></p>
  <p>I'm not using latest version of <code>url_launcher</code> so may be using latest version will solve the issue BUT problem with it is that latest version of  <code>url_launcher</code> needs latest version of flutter. Is it safe to upgrade flutter version? I can't take a risk of causing any more issues as my app is already in production</p>
  <p>This is what I get when I try to upgrade to  <code>url_launcher: ^5.7.10</code> which is the latest version and run <strong>flutter pub get</strong></p>
  <pre><code>[xxxxx] flutter pub get
  Running &quot;flutter pub get&quot; in xxxxx...                       
  The current Flutter SDK version is 1.22.0-9.0.pre.
  
  Because url_launcher &gt;=5.7.7 &lt;6.0.0-nullsafety depends on url_launcher_platform_interface &gt;=1.0.9 &lt;2.0.0-nullsafety which requires Flutter SDK version &gt;=1.22.0 &lt;2.0.0, url_launcher &gt;=5.7.7 &lt;6.0.0-nullsafety is forbidden.
  
  So, because xxxxx depends on url_launcher ^5.7.10, version solving failed.
  pub get failed (1; So, because storeifie depends on url_launcher ^5.7.10, version solving failed.)
  exit code 1
  </code></pre>