Add Anytools Regex Tester to Regex section

[RyanCadev]

Adds Anytools Regex Tester — a direct link to a single, specific tool.

• Browser-based — no downloads or native app installs
• Direct link — goes straight to the regex tester tool, not a landing page
• 100% free — no signups, trials, paywalls, or usage limits

Live JavaScript regex matching with capture group highlighting. 100% client-side, no data sent to servers.

[github-actions]

Hey RyanCadev! Thanks for your submission! 🚀

To keep awesome-devtools instantly accessible for everyone, all tools must be:

• Browser-based — no downloads or native app installs
• Direct link — goes straight to the tool (not a multi-tool landing page)
• 100% free — no signups, trials, paywalls, or usage limits

Please make sure your PR meets these criteria. It may take some time for your submission to be reviewed — you can occasionally comment with a "bump" to bring more attention to it.

Thanks for contributing! 🙌