downloads: upgrade to CPython 3.7.6

We should always use the latest version.

Author: indygreg

pythonbuild/downloads.py

@@ -65,10 +65,10 @@
         "version": "3.15.1",
     },
     "cpython-3.7": {
-        "url": "https://www.python.org/ftp/python/3.7.5/Python-3.7.5.tar.xz",
-        "size": 17236432,
-        "sha256": "e85a76ea9f3d6c485ec1780fca4e500725a4a7bbc63c78ebc44170de9b619d94",
-        "version": "3.7.5",
+        "url": "https://www.python.org/ftp/python/3.7.6/Python-3.7.6.tar.xz",
+        "size": 17246360,
+        "sha256": "55a2cce72049f0794e9a11a84862e9039af9183603b78bc60d89539f82cf533f",
+        "version": "3.7.6",
         "licenses": ["Python-2.0", "CNRI-Python"],
         "license_file": "LICENSE.cpython.txt",
     },