ci(actions): run checkout and yarn install

Author: wopian

.github/workflows/jest.yml

@@ -2,8 +2,11 @@ name: CI
 on: [ push, pull_request ]
 jobs:
   jest:
+    name: Jest Coverage
     runs-on: ubuntu-latest
     steps:
+    - uses: actions/checkout@v1
+    - run: yarn
     - name: Jest Coverage
       uses: mattallty/jest-github-action@v1
       continue-on-error: true