Bug Fix: Stepping into lava is now penalized by the health reward in Craftax Classic (#50) (#51)

* Add lava penalty to craftax classic (#50)

Stepping into lava now reduces health to 0, allowing it to be penalized by the health reward.

* also fix negative health bug

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Co-authored-by: MichaelTMatthews <michael.tryfan.matthews@gmail.com>