package/python3: bump to 3.6.2

package/python3: bump to 3.6.2

Bump Python3 version to 3.6.2.

Patches dropped:

"Support PGEN_FOR_BUILD and FREEZE_IMPORTLIB_FOR_BUILD"

Rationale: With commit 9d02f562961efd12d3c8317a10916db7f77330cc, code
generation step of building CPython now became explicit (instead of
always performed as a part of 'make' invocation) and more granular. We
no longer need to use Parser/pgen at all and tricking the build system
into using different Programs/_freeze_importlib can be done as a part
of recipe.

Additional info about the build change can be found at
https://bugs.python.org/issue23404

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Tested-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>