Update Ministro's repo

Change-Id: I090e1c856f7a93a2a7d8c715c779fc07ce351361
Reviewed-by: Christian Stromme <christian.stromme@qt.io>

src/android/templates/res/values/libs.xml

 <?xml version='1.0' encoding='utf-8'?>
 <resources>
     <array name="qt_sources">
-        <item>https://download.qt.io/ministro/android/qt5/qt-5.6</item>
+        <item>https://download.qt.io/ministro/android/qt5/qt-5.7</item>
     </array>
 
     <!-- The following is handled automatically by the deployment tool. It should