Add icons: powerbi, excel, seaborn, tableau

[theharshchandrakar]

Adds four new icons and their metadata to devicon.json.

What I changed:

Added devicon entries for:

• powerbi — svg variants: original, original-wordmark
• excel — svg variant: original
• seaborn — svg variants: original, original-wordmark
• tableau — svg variants: original, original-wordmark

Updated devicon.json to include entries with tags, versions, colors (where applicable), and aliases mapping original → original-wordmark for wordmark variants.

Files included in this PR:

• devicon.json (updated to add the four new icon objects)
• (plus the SVG files you committed under icons/* — e.g., icons/powerbi/, icons/excel/, icons/seaborn/, icons/tableau/)

Notes for reviewers:

• Colors: I set Excel (#217346), Power BI (#F2C811), Tableau (#E97627). Seaborn has color: null because the project has no single official brand color — happy to set a hex if you prefer a specific color.
• Each wordmark variant is added as an alias from the base "original" (aliases: { base: "original", alias: "original-wordmark" }).
• Ensure SVG files exist at the expected paths (icons//.svg). If file names differ, I can adjust the devicon.json entries.

[weh]

Hi @Rikashiii, thank you for the contribution. Unfortunately there are many points here, that do not match our guidelines.

• please create a PR for every icon
• Excel, PowerBI and Tableau will not match our acceptance guidelines for Developer related tools
• Seaborn icon already has a open PR: #2485

For the next time, check our wiki and contribution guidelines to prevent contributions which can not be accepted.