fix: specify the color-scheme for dark mode

[LitoMore]

PR Checklist

• The PR title follows
  conventional commits
• Is this closing an open issue? If so, link it, else include a proper
  description of the changes and rason behind them.
• Does the PR have changes to the frontend? If so, include screenshots or a
  recording of the changes.
  
  If it affect colors, please include screenshots/recording in both
  light and dark mode.
• Does the PR have changes to the backend? If so, make sure tests are added.
  
  And if changing dababase queries, be sure you have ran sqlx prepare
  and committed the changes in the .sqlx directory.

How to reproduce this issue

(Safari does not support this, you need to use Chrome or Firefox to reproduce this issue)

1. Switch to dark mode
2. Modify any img src to https://cdn.simpleicons.org/jsr/yellow/blue in your inspector
3. The image color should be blue, but it's yellow on production

Description

The package readme may include a dynamic color scheme style in the image, like this project's readme: https://github.com/LitoMore/simple-icons-cdn.

This PR fixes a display behavior when the remote image has a prefers-color-scheme inside for dark mode.

Preview

Before	After