Update max-version in setup.py to 3.9 (#54690)

Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/54690

Reviewed By: seemethere

Differential Revision: D27330462

Pulled By: malfet

fbshipit-source-id: db332acf5aa5bff67af2bef777935f2387bc963c
diff --git a/setup.py b/setup.py
index aebbab3..e89909e 100644
--- a/setup.py
+++ b/setup.py
@@ -883,7 +883,7 @@
     with open(os.path.join(cwd, "README.md"), encoding="utf-8") as f:
         long_description = f.read()
 
-    version_range_max = max(sys.version_info[1], 8) + 1
+    version_range_max = max(sys.version_info[1], 9) + 1
     setup(
         name=package_name,
         version=version,