pip: bump regex from 2026.2.19 to 2026.2.28

Bumps [regex](https://github.com/mrabarnett/mrab-regex) from 2026.2.19 to 2026.2.28.
- [Changelog](https://github.com/mrabarnett/mrab-regex/blob/hg/changelog.txt)
- [Commits](mrabarnett/mrab-regex@2026.2.19...2026.2.28)

---
updated-dependencies:
- dependency-name: regex
  dependency-version: 2026.2.28
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

pip-requirements.txt

@@ -15,5 +15,5 @@
 edk2-pytool-library==0.23.11
 edk2-pytool-extensions==0.30.8
 antlr4-python3-runtime==4.13.2
-regex==2026.2.19
+regex==2026.2.28
 pygount==3.1.1