Trying to fix python 3.7 build on Travis

.travis.yml

@@ -3,15 +3,13 @@ sudo: false
 install: "pip install -r requirements.txt"
 script: nosetests dnstraceroute.py
 matrix:
-    fast_finish: true
-    include:
-        - python: "3.3"
-        - python: "3.4"
-        - python: "3.5"
-        - python: "3.6"
-        - python: "3.7"
-        - python: "3.8-dev"
-        - python: "pypy3"
-          dist: xenial
-          sudo: true
-
+  fast_finish: true
+  include:
+    - python: "3.3"
+    - python: "3.4"
+    - python: "3.5"
+    - python: "3.6"
+    - python: "pypy3"
+    - python: 3.7
+      dist: xenial
+      sudo: true