schema: mysql: remove foreign key to ttrss_themes before dropping theme_id from ttrss_users

schema/versions/mysql/83.sql

@@ -24,7 +24,9 @@ update ttrss_feeds set pubsub_state = 0;
 alter table ttrss_feeds change pubsub_state pubsub_state integer not null;
 alter table ttrss_feeds alter column pubsub_state set default 0;
 
+alter table ttrss_users drop foreign key ttrss_users_ibfk_1
 alter table ttrss_users drop column theme_id;
+
 drop table ttrss_themes;
 
 update ttrss_version set schema_version = 83;