v1.4.0

Changelog:

• I've upgraded the engine to the latest version of Godot, hopefully some performance improvements might come through. If you see any weird new bugs that might have been caused by the update then please report them on Discord or the discussion board :)
• Slightly reduced later boss health (level 4 onwards)
• Slightly reduced miniboss health
• Slightly increased Dash and Flash item cooldowns
• Attempted to soften the coin SFX a touch