add 500px icon

[saeedesmaili]

What does this PR change? What problem does it solve?

• Add social icon for 500px
• Raw SVG source: https://simpleicons.org/?q=500px

Was the change discussed in an issue or in the Discussions before?

No

PR Checklist

• [ ] This change adds/updates translations and I have used the template present here.
• [x] I have enabled maintainer edits for this PR.
• [x] I have verified that the code works as described/as intended.
• [x] This change adds a Social Icon which has a permissive license to use it.
• [x] This change does not include any CDN resources/links.
• [x] This change does not include any unrelated scripts such as bash and python scripts.
• [ ] This change updates the overridden internal templates from HUGO's repository.

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud

[sonarcloud[bot]]

Quality Gate failed

Failed conditions
E Maintainability Rating on New Code (required ≥ A)

See analysis details on SonarCloud

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