python: update 3.8.5 -> 3.9.0

Drop 0001-Do-not-hardcode-lib-as-location-for-site-packages-an.patch,
0001-configure.ac-fix-LIBPL.patch and 0001-python3-Do-not-hardcode-lib-for-distutils.patch
as they are all replaced by the new --platlibdir option to ./configure

Rename 0001-Lib-sysconfig.py-fix-another-place-where-lib-is-hard.patch to
0001-Lib-sysconfig.py-use-libdir-values-from-configuratio.patch
and describe the changes better.

License-Update: documentation now dual license under PSF & BSD
(not relevant for the recipe.
(From OE-Core rev: 7347556b18b45c5f9afc2cade565a75c95876914)

Signed-off-by: Alexander Kanavin <alex.kanavin@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/python/python3/0001-Don-t-search-system-for-headers-libraries.patch

@@ -1,4 +1,4 @@
-From b880e78bf4a1852e260188e6df3ec6034403d2fc Mon Sep 17 00:00:00 2001
+From 9da913bf5f39c6fe737219af7419170574d6fbfb Mon Sep 17 00:00:00 2001
 From: Jeremy Puhlman <jpuhlman@mvista.com>
 Date: Wed, 4 Mar 2020 00:06:42 +0000
 Subject: [PATCH] Don't search system for headers/libraries
@@ -11,7 +11,7 @@ Signed-off-by: Jeremy Puhlman <jpuhlman@mvista.com>
  1 file changed, 2 insertions(+), 2 deletions(-)
 
 diff --git a/setup.py b/setup.py
-index 7208cd0..c0bd0ad 100644
+index a0bf9ea..da099bf 100644
 --- a/setup.py
 +++ b/setup.py
 @@ -674,8 +674,8 @@ class PyBuildExt(build_ext):