feat: add CircleCI config explicit resource class

Author: simonsdave

.circleci/config.yml

@@ -18,6 +18,7 @@ executors:
         auth:
           username: $DOCKER_EXECUTOR_DOCKERHUB_USERNAME
           password: $DOCKER_EXECUTOR_DOCKERHUB_PASSWORD
+    resource_class: medium
 
 jobs:
   build_test_and_deploy:

CHANGELOG.md

@@ -14,6 +14,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
   runtime and runtime lite docker images - very useful during
   development when upgrading major things like Python and/or OS
   versions
+* added explicit [resource class](https://circleci.com/docs/2.0/configuration-reference/#resourceclass)
+  to CircleCI config
 
 ### Changed