Change path to network.example.json.

When the repo was rearranged, it broke a unit test that expected
to find network.json.example in the "1.3" folder. It now looks
in the src/ folder, and the test passes.

src/testGraph.py

@@ -252,7 +252,7 @@ class TestGraph(unittest.TestCase):
         net.createNetworkJson()
         with open('network.json') as file:
             newFile = json.load(file)
-        with open('v1.3/network.example.json') as file:
+        with open('src/network.example.json') as file:
             exampleFile = json.load(file)
         self.assertEqual(newFile, exampleFile)