[linux] Update logo

[rcalixte]

Please confirm this pull request meets the following requirements:

• I followed the contributing guidelines: https://github.com/github/explore/blob/main/CONTRIBUTING.md.
• I am not the sole author or employee of a company who created either the topic I am modifying/adding or the collection entry I am modifying/adding.

Which change are you proposing?

• Suggesting edits to an existing topic or collection

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Editing an existing topic or collection

I'm suggesting these edits to an existing topic or collection:

• Image (and my file is *.png, square, dimensions 288x288, size <= 75 kB)

This logo removes the heavy white background in favor of a simple border. This avoids clashing on dark backgrounds.

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Please note: we will close your PR without comment if you do not check the boxes above and provide ALL requested information.

[ahpook]

LGTM

For what it's worth - when you have numerous small changes like these logo updates, feel free to batch them into one PR. Thank you for the contributions!

[rcalixte]

For what it's worth - when you have numerous small changes like these logo updates, feel free to batch them into one PR. Thank you for the contributions!

Thank you! I'd debated this as it started as one and then another... and then I got carried away. 😅