remove 3.7-dev and 3.8-dev from travis py vers

Author: Someguy123

.travis.yml

@@ -8,8 +8,6 @@ python:
   - "3.6"
   - "3.7"
   - "3.8"
-  - "3.7-dev"
-  - "3.8-dev"
   - "nightly"
 before_install:
   - sudo apt-get update -qy