Use mysql_native_password as default authentication plugin

Signed-off-by: Daniel Kesselberg <mail@danielkesselberg.de>

.drone.yml

@@ -486,6 +486,7 @@ services:
   image: redis
 - name: mysql
   image: mysql:8.0
+  command: [ "--default-authentication-plugin=mysql_native_password" ]
   environment:
     MYSQL_ROOT_PASSWORD: owncloud
     MYSQL_USER: oc_autotest