Sprite changes to summonable's drops (Monkestation#1281)

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## About The Pull Request
This changes some sprites in natural.dm, particularly those dropped by
summons,
see details for sprite comparison.
<details> 
sprites before:

![Screenshot 2025-04-01
021530](https://github.com/user-attachments/assets/e4cc3b56-dcc8-48ce-a713-d88a2b3a1c0c)

sprites after:

![Screenshot 2025-04-01
021514](https://github.com/user-attachments/assets/f78c48c2-5d5a-423f-b92f-3df0c62d5805)

</details>
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## Why It's Good For The Game

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## Pre-Merge Checklist
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- [x] You tested this on a local server.
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Author: Viviridia