python3: Update to 3.7.8, refresh/rework patches

This contains a fix for CVE-2020-8492 (Denial of service in
urllib.request.AbstractBasicAuthHandler)[1].

This also updates the setuptools and pip packages to 47.1.0 and 20.1.1,
respectively.

[1]: https://docs.python.org/release/3.7.8/whatsnew/changelog.html#python-3-7-8-release-candidate-1

Signed-off-by: Jeffery To <jeffery.to@gmail.com>

lang/python/python3/patches-setuptools/004-site-patch.patch

@@ -1,6 +1,6 @@
 --- a/setuptools/command/easy_install.py
 +++ b/setuptools/command/easy_install.py
-@@ -1315,7 +1315,10 @@ class easy_install(Command):
+@@ -1324,7 +1324,10 @@ class easy_install(Command):
              return  # already did it, or don't need to
  
          sitepy = os.path.join(self.install_dir, "site.py")