Add sale_promotion as tests_require

setup.py

@@ -52,7 +52,7 @@ for dep in info.get('depends', []):
 requires.append(get_require_version('trytond'))
 
 tests_require = [get_require_version('proteus')]
-for dep in ['account', 'party', 'stock']:
+for dep in ['account', 'party', 'stock', 'sale_promotion']:
     tests_require.append(get_require_version('trytond_%s' % dep))
 dependency_links = []
 if minor_version % 2: