build(deps): bump regex from 2021.8.3 to 2021.8.28

Bumps [regex](https://bitbucket.org/mrabarnett/mrab-regex) from 2021.8.3 to 2021.8.28.
- [Commits](https://bitbucket.org/mrabarnett/mrab-regex/commits)

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

Signed-off-by: dependabot[bot] <[email protected]>

requirements.txt

@@ -33,7 +33,7 @@ pyparsing==2.4.7
 pytest==6.2.3
 pytest-cov==2.11.1
 PyYAML==5.4.1
-regex==2021.8.3
+regex==2021.8.28
 requests==2.26.0
 six==1.16.0
 toml==0.10.2