ci: removes node 4 tests

circle.yml

@@ -11,7 +11,6 @@ dependencies:
       if [[ ! -e ~/.yarn/bin/yarn || $(yarn --version) != "${YARN_VERSION}" ]]; then
         curl -o- -L https://yarnpkg.com/install.sh | bash -s -- --version $YARN_VERSION
       fi
-    - nvm install 4
     - nvm install 6
 
   cache_directories:
@@ -25,8 +24,6 @@ test:
     - yarn run pre:ci
     - nvm alias default 6
     - yarn run test
-    - nvm alias default 4
-    - yarn run test
     - nvm alias default 8
     - yarn run test
 deployment: