add gitguardian action

.github/workflows/ci.yml

@@ -37,3 +37,18 @@ jobs:
     - run: yarn percy
       env:
         PERCY_TOKEN: ${{ secrets.PERCY_TOKEN }}
+
+  audit:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        fetch-depth: 0
+    - name: GitGuardian scan
+      uses: GitGuardian/gg-shield-action@master
+      env:
+        GITHUB_PUSH_BEFORE_SHA: ${{ github.event.before }}
+        GITHUB_PUSH_BASE_SHA: ${{ github.event.base }}
+        GITHUB_PULL_BASE_SHA:  ${ github.event.pull_request.base.sha }}
+        GITHUB_DEFAULT_BRANCH: ${ github.event.repository.default_branch }}
+        GITGUARDIAN_API_KEY: ${ secrets.GITGUARDIAN_API_KEY }}