Update python 3.6 -> 3.8

Selections is now running on 3.8 in OKD, so ci should match that

Author: mxmeinhold

.travis.yml

@@ -1,6 +1,6 @@
 language: python
 python:
-  - "3.6"
+  - "3.8"
 
 install:
   - "pip install -r requirements.txt"

README.md

@@ -1,5 +1,5 @@
 # Selections
-[![Python 3.6](https://img.shields.io/badge/python-3.6-blue.svg)](https://www.python.org/downloads/release/python-360/)
+[![Python 3.8](https://img.shields.io/badge/python-3.8-blue.svg)](https://www.python.org/downloads/release/python-380/)
 [![Build Status](https://travis-ci.org/ComputerScienceHouse/csh-selections.svg?branch=develop)](https://travis-ci.org/ComputerScienceHouse/csh-selections)
 
 Selections is a Flask / Python web app meant to help facilitate the application review process for Computer Science House.