Removed unused TF imports to pass pyflakes

Author: matthewfeickert

tests/conftest.py

@@ -1,6 +1,5 @@
 import pytest
 import pyhf
-import tensorflow as tf
 import sys
 
 

tests/test_backend_consistency.py

@@ -1,5 +1,4 @@
 import pyhf
-import tensorflow as tf
 import numpy as np
 import pytest