Fix nox python docs version

Author: staticdev

noxfile.py

@@ -157,7 +157,7 @@ def xdoctest(session: Session) -> None:
     session.run("python", "-m", "xdoctest", package, *args)
 
 
-@nox.session(name="docs-build", python="3.8")
+@nox.session(name="docs-build", python="3.9")
 def docs_build(session: Session) -> None:
     """Build the documentation."""
     args = session.posargs or ["docs", "docs/_build"]
@@ -171,7 +171,7 @@ def docs_build(session: Session) -> None:
     session.run("sphinx-build", *args)
 
 
-@nox.session(python="3.8")
+@nox.session(python="3.9")
 def docs(session: Session) -> None:
     """Build and serve the documentation with live reloading on file changes."""
     args = session.posargs or ["--open-browser", "docs", "docs/_build"]