Merge pull request #266 from DimitrisJim/add_3.9_feature

Expose python3.9 feature.

Author: markbt

Cargo.toml

@@ -85,6 +85,7 @@ py-link-mode-unresolved-static = [ "python3-sys/link-mode-unresolved-static" ]
 # Optional features to support explicitly specifying python minor version.
 # If you don't care which minor version, just specify python3-sys as a 
 # feature.
+python-3-9 = ["python3-sys/python-3-9"]
 python-3-8 = ["python3-sys/python-3-8"]
 python-3-7 = ["python3-sys/python-3-7"]
 python-3-6 = ["python3-sys/python-3-6"]