Fix import order.

Author: Luke Sneeringer

api_core/tests/unit/gapic/test_dispatch.py

@@ -12,11 +12,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from google.api_core.gapic_v1.dispatch import dispatch
-
 import pytest
 import six
 
+from google.api_core.gapic_v1.dispatch import dispatch
+
 
 @pytest.mark.skipif(six.PY2, reason='dispatch only works on Python 3.')
 def test_dispatch():