Bump tinycss2 from 1.4.0 to 1.5.1

Bumps [tinycss2](https://github.com/Kozea/tinycss2) from 1.4.0 to 1.5.1.
- [Release notes](https://github.com/Kozea/tinycss2/releases)
- [Changelog](https://github.com/Kozea/tinycss2/blob/main/docs/changelog.rst)
- [Commits](Kozea/tinycss2@v1.4.0...v1.5.1)

---
updated-dependencies:
- dependency-name: tinycss2
  dependency-version: 1.5.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

requirements.txt

@@ -96,6 +96,6 @@ django-contact-us==1.1.0
 entrypoints==0.4
 
 webencodings==0.5.1 # django-markdownify
-tinycss2==1.4.0 # django-markdownify
+tinycss2==1.5.1 # django-markdownify
 bleach==6.3.0 # django-markdownify
 django-markdownify==0.9.6