devel/py-colorama: Fix build with Python 3.6

* Backport PR #294 [1] from upstream repository to enable default UTF-8
  encoding in setup.py which fixes the build issue with Python 3.6.

PR:		252294, 251240 [2]
Submitted by:	John W. O'Brien [1]
Reported by:	Dani <i.dani@outlook.com> [2]
Reviewed by:	koobs, ygy
Approved by:	portmgr (blanket: build fix)

devel/py-colorama/files/patch-setup.py

@@ -0,0 +1,26 @@
+Default to UTF-8 encoding to fix build with Python 3.6
+
+Obtained from: https://github.com/tartley/colorama/pull/294/files
+
+--- setup.py.orig	2020-10-12 21:22:32 UTC
++++ setup.py
+@@ -3,6 +3,7 @@
+ 
+ from __future__ import with_statement
+ 
++from io import open
+ import os
+ import re
+ try:
+@@ -14,8 +15,9 @@ except ImportError:
+ NAME = 'colorama'
+ 
+ 
+-def read_file(path):
+-    with open(os.path.join(os.path.dirname(__file__), path)) as fp:
++def read_file(path, encoding='utf8'):
++    with open(os.path.join(os.path.dirname(__file__), path),
++              encoding=encoding) as fp:
+         return fp.read()
+ 
+ def _get_version_match(content):