new icon: celery (original, original-wordmark, plain, plain-wordmark)

[star-lord1234]

Double check these details before you open a PR

• PR does not match another non-stale PR currently opened
• PR name matches the format new icon: Icon name (versions separated by comma). More details here
• PR's base is the develop branch.
• Your icons are inside a folder as seen here
• SVG matches the standards laid out here
• A new object is added in the devicon.json file at the correct alphabetic position as seen here

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Link to prove your SVG is correct and up-to-date.

Description

This PR adds a new icon for Celery, including:

• icons/celery/celery-original.svg
• icons/celery/celery-wordmark.svg

The SVGs are optimized, validated against the W3C checker, and under 1KB in size.

Checklist

• Icon files are in the correct folder (icons/celery/)
• SVGs are under 1KB
• SVGs pass W3C validation
• Readme updated automatically by CI