update README

Author: erikng

README.md

@@ -34,7 +34,7 @@ remote: Counting objects: 100% (20/20), done.
 remote: Compressing objects: 100% (14/14), done.
 remote: Total 70 (delta 7), reused 16 (delta 6), pack-reused 50
 Unpacking objects: 100% (70/70), done.
-Downloading https://www.python.org/ftp/python/3.7.4/python-3.7.4-macosx10.9.pkg...
+Downloading https://www.python.org/ftp/python/3.8.0/python-3.8.0-macosx10.9.pkg...
 
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