Remove unused dependency (opentracing#22)

bhs · web-flow · commit 7cd6fa73bb46 · 2017-05-28T15:03:42.000-07:00
Closes opentracing#21.
diff --git a/setup.py b/setup.py
@@ -21,7 +21,6 @@
     zip_safe=False,
     platforms='any',
     install_requires=[
-        'futures',
         'protobuf>=3.0.0b2.post2',
         'opentracing>=1.2.1,<1.3',
         'six>=1.10.0,<2.0',
