Fix migration

Fixes #6695
// FREEBIE

src/org/thoughtcrime/securesms/database/DatabaseFactory.java

@@ -875,7 +875,7 @@ public class DatabaseFactory {
         db.execSQL("ALTER TABLE identities ADD COLUMN blocking_approval INTEGER DEFAULT 0");
         db.execSQL("ALTER TABLE identities ADD COLUMN nonblocking_approval INTEGER DEFAULT 0");
 
-        db.execSQL("DROP INDEX archived_count_index");
+        db.execSQL("DROP INDEX archived_index");
         db.execSQL("CREATE INDEX IF NOT EXISTS archived_count_index ON thread (archived, message_count)");
 
         db.execSQL("UPDATE identities SET blocking_approval = '1'");