Dead Spider Sprite Fix (cmss13-devs#4585)

# About the pull request

Dead spiders had white pixels where there should be transparent pixels.

# Explain why it's good for the game

Sprite bug fix gud


# Testing Photographs and Procedure
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<summary>Screenshots & Videos</summary>

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screenshots and the `<details>` tags.

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# Changelog

:cl:
fix: fixed spider dead sprite to not have white space (is transparent
instead)
/:cl: