Update set max width of message content to 80 percent (#5342)

# Description
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dependencies that are required for this change. -->

I limited the max width.

**Type of change**
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PR according to the type of change -->

- Bug fix (non-breaking change which fixes an issue)

**How Has This Been Tested**
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**Checklist**
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- I added relevant documentation
- I followed the style guidelines of this project
- I did a self-review of my code
- I made corresponding changes to the documentation
- I confirm My changes generate no new warnings
- I have added tests that prove my fix is effective or that my feature
works
- I have added relevant notes to the CHANGELOG.md file (See
https://keepachangelog.com/)

argilla/src/argilla/markdown/chat.py

@@ -39,7 +39,7 @@
         .message-content {
             padding: 10px;
             border-radius: 10px;
-            max-width: fit-content;
+            max-width: 80%;
         }
     </style>
     """