Fixes open-keychain/open-keychain#1515

Move launcher icons to mipmap

OpenKeychain/src/main/res/xml/account_desc.xml

@@ -2,5 +2,5 @@
 <account-authenticator xmlns:android="http://schemas.android.com/apk/res/android"
     android:accountPreferences="@xml/account_preferences"
     android:accountType="@string/account_type"
-    android:icon="@drawable/ic_launcher"
+    android:icon="@mipmap/ic_launcher"
     android:label="@string/app_name" />