Add flag value to database

Unfortunately required, as loadBeatmaps() refreshes the decoded beatmap
with the database-stored values, which can end up overwriting the
decoded ones.

osu.Game/Migrations/OsuDbContextModelSnapshot.cs

@@ -57,6 +57,8 @@ namespace osu.Game.Migrations
 
                     b.Property<double>("DistanceSpacing");
 
+                    b.Property<bool>("EpilepsyWarning");
+
                     b.Property<int>("GridSize");
 
                     b.Property<string>("Hash");