downloads: upgrade CPython 3.8 to 3.8.0

3.8.0 has been released. Let's use it.

Author: indygreg

pythonbuild/downloads.py

@@ -73,10 +73,10 @@
         "license_file": "LICENSE.cpython.txt",
     },
     "cpython-3.8": {
-        "url": "https://www.python.org/ftp/python/3.8.0/Python-3.8.0b3.tar.xz",
-        "size": 17768608,
-        "sha256": "cd7a81efcc9f82e20f9d6a41fd6f9859ddc2a082dcbc3fa62932e53b6f41980f",
-        "version": "3.8.0b3",
+        "url": "https://www.python.org/ftp/python/3.8.0/Python-3.8.0.tar.xz",
+        "size": 17829824,
+        "sha256": "b356244e13fb5491da890b35b13b2118c3122977c2cd825e3eb6e7d462030d84",
+        "version": "3.8.0",
         "licenses": ["Python-2.0", "CNRI-Python"],
         "license_file": "LICENSE.cpython.txt",
     },