Tests passing for all Python versions >= 3.6 (nficano#487)

* Allowing all Python versions

* Removing Python 3.5 from travis config file since it is not supported by AWS Lambda

* Updating readme

* Escaping the tilde for the benefit of my code editor

Author: rishabh-bhargava

.travis.yml

@@ -3,13 +3,12 @@ cache:
   - apt
   - pip
 python:
-  - "3.5"
   - "3.6"
   - "3.7"
-  - "3.8" 
+  - "3.8"
 before_install:
   - pip install pipenv --upgrade
-script: 
+script:
   - pipenv install --dev
   - pytest
 sudo: false

Pipfile

@@ -26,8 +26,5 @@ pyaml = "==15.8.2"
 python-dateutil = "==2.5.3"
 PyYAML = "==5.1"
 
-[requires]
-python_version = "3.8"
-
 [pipenv]
 allow_prereleases = true