Update Elixir icon - #15021

Issue: none, color update for an existing icon

Popularity metric: n/a, existing icon

Terms of Service link: https://elixir-lang.org/trademarks/ ("Inclusion of the Elixir logo in non-commercial icon sets" is explicitly permitted)

Checklist

• I have reviewed the forbidden brands list and confirm the brand I am submitting a PR for is not one of them, nor is it a subsidiary of one of those brands
• I have reviewed the brand's terms of service, and am confident we can add this icon
• I confirm that I did not use AI tools to create this PR, or that any AI assistance has been fully disclosed in this PR
• I updated the JSON data in data/simple-icons.json
• I optimized the icon with SVGO or SVGOMG (icon unchanged)
• The SVG viewbox is 0 0 24 24 (icon unchanged)

Description

Elixir got a new logo with the July website redesign and the Elixir team now publishes an official brand color, #8847B9, on its trademarks page. This updates the hex to match and adds that page as guidelines. The icon itself is unchanged, the silhouette still matches the new mark.

AI disclosure: the JSON edit was prepared with Claude Code and reviewed by me. I'm a member of the Elixir team.