Bump typing-extensions from 4.8.0 to 4.9.0 (#181)

Author: dependabot[bot]

docs/requirements.txt

@@ -8,5 +8,5 @@ sphinx-copybutton==0.5.2
 sphinxcontrib-mermaid==0.9.2
 
 # auxiliary
-typing-extensions==4.8.0
+typing-extensions==4.9.0
 mypy-extensions==1.0.0