Switch to poetry

Author: craigloftus

.travis.yml

@@ -1,8 +1,10 @@
 language: python
 python:
- - "3.6"
- - "3.7"
- - "3.8"
- - "3.9"
-install: pip install tox-travis
+ - 3.6
+ - 3.7
+ - 3.8
+ - 3.9
+before_install:
+ - pip install --upgrade pip
+ - pip install poetry tox-travis
 script: tox