Bump python-slugify from 3.0.4 to 3.0.6

Bumps [python-slugify](https://github.com/un33k/python-slugify) from 3.0.4 to 3.0.6.
- [Release notes](https://github.com/un33k/python-slugify/releases)
- [Changelog](https://github.com/un33k/python-slugify/blob/master/CHANGELOG.md)
- [Commits](un33k/python-slugify@3.0.4...3.0.6)

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

requirements.txt

@@ -14,7 +14,7 @@ hyperlink==19.0.0
 idna>=2.5,<2.9
 urllib3==1.25.6
 Paver==1.3.4
-python-slugify==3.0.4
+python-slugify==3.0.6
 decorator==4.4.0
 celery==4.2.1
 kombu==4.6.5