fix: install python-requests for backend

CHANGELOG.md

@@ -4,6 +4,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 Which is based on [Keep A Changelog](http://keepachangelog.com/)
 
 ## [Unreleased]
+- fix: install python-requests for backend
 
 ## [1.0.0] - 2019-02-06
 - first version

tasks/backend.yml

@@ -6,6 +6,7 @@
     packages:
       - sensu-go-backend
       - sensu-go-cli
+      - python-requests
   register: result
   retries: 3
   delay: 1

test/integration/default/serverspec/default_spec.rb

@@ -12,6 +12,7 @@ puts '================================'
   sensu-go-cli
   sensu-go-backend
   monitoring-plugins-basic
+  python-requests
 ].each do |package|
   describe package(package) do
     it { should be_installed }