Update minimum PBR for setup_requires

Some of the recently-added Python package metadata (particularly
project_urls and description-content-type) need newer PBR where that
support was added. PBR 5.0.0 is the oldest version with the
particular features we're using, so update the lower bound for it
accordingly.

diff --git a/setup.py b/setup.py
index 9288753..0ee8be3 100644 (file)
--- a/setup.py
+++ b/setup.py
@@ -1,7 +1,7 @@
-# Copyright (c) 2016 mudpy authors. Permission to use, copy,
+# Copyright (c) 2016-2019 mudpy authors. Permission to use, copy,
 # modify, and distribute this software is granted under terms
 # provided in the LICENSE file distributed with this software.
 
 import setuptools
 
-setuptools.setup(setup_requires=['pbr>=2.0'], pbr=True)
+setuptools.setup(setup_requires=['pbr>=5'], pbr=True)