fix: add install a package to improve the accuracy of guessing mime type and file extension

[kurokobo]

Summary

This is for plugins/beta branch.

This PR installs media-types package to improve the accuracy of guessing mime type and file extension.
When creating a file in the tool plugin, we can specify the mime type for the file, but due to the lack of media-types package, even if we provide the correct mime type, the file extension may become .bin in some cases.

Screenshots

Before
Without media-types, mimetypes module in Python cannot guess the extension for the specific mime types:

After
By installing media-types package, the extension for the specific mime types can be guessed:

Checklist

Important

Please review the checklist below before submitting your pull request.

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

[kurokobo]

The lint error is for models/dataset.py which is not related to this PR.