Removed circle CI (#4236)

.circleci/config.yml

@@ -1,20 +0,0 @@
-version: 2
-jobs:
-  build:
-    docker:
-      - image: circleci/node:12
-    steps:
-      - checkout
-      - restore_cache:
-          keys:
-            - dependencies-{{ checksum "yarn.lock" }}
-      - run:
-          name: Install
-          command: yarn install --pure-lockfile
-      - save_cache:
-          paths:
-            - node_modules
-          key: dependencies-{{ checksum "yarn.lock" }}
-      - run:
-          name: Check Prettier, ESLint, Flow
-          command: yarn ci-check