Update pyyaml requirement from <5.5,>=5.1 to >=5.1,<6.1

Updates the requirements on [pyyaml](https://github.com/yaml/pyyaml) to permit the latest version.
- [Release notes](https://github.com/yaml/pyyaml/releases)
- [Changelog](https://github.com/yaml/pyyaml/blob/master/CHANGES)
- [Commits](yaml/pyyaml@5.1...6.0)

---
updated-dependencies:
- dependency-name: pyyaml
  dependency-type: direct:production
...

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

Author: dependabot[bot]

setup.py

@@ -12,7 +12,7 @@
         'djangorestframework>=3.10,<4.0',
         'structlog<21.2.0',
         'jinja2<2.12',
-        'PyYAML>=5.1,<5.5',
+        'PyYAML>=5.1,<6.1',
         'PyStaticConfiguration==0.10.5',
         'requests<2.26',
         'PyConfigure==0.5.9',