chore(deps-dev): update pyyaml requirement from <6.0.0 to <7.0.0

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@3.01...6.0)

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

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

setup.py

@@ -43,7 +43,7 @@
             "pre-commit==1.20.0",
             "pytest==5.2.4",
             "pydoc-markdown==2.0.5",
-            "pyyaml<6.0.0",
+            "pyyaml<7.0.0",
             "six==1.12.0",
             "tabulate==0.8.7",
             "xlrd==1.2.0",