di: update livecheck

[samford]

• Have you followed the guidelines for contributing?
• Have you ensured that your commits follow the commit style guide?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with HOMEBREW_NO_INSTALL_FROM_API=1 brew install --build-from-source <formula>, where <formula> is the name of the formula you're submitting?
• Is your test running fine brew test <formula>, where <formula> is the name of the formula you're submitting?
• Does your build pass brew audit --strict <formula> (after doing HOMEBREW_NO_INSTALL_FROM_API=1 brew install --build-from-source <formula>)? If this is a new formula, does it pass brew audit --new <formula>?

---

This is a follow-up to #205859, as it was merged before I was able to review it.

The livecheck block for di was recently modified to check loose version text on the homepage, as the existing Sourceforge check was returning an unstable 4.99.5 version from the /beta subdirectory as newest. This addresses the issue by updating the previous Sourceforge check's regex to only target matching tarballs in the root directory.