add size action

.github/workflows/size.yml

@@ -0,0 +1,12 @@
+name: size
+on: [pull_request]
+jobs:
+  size:
+    runs-on: ubuntu-latest
+    env:
+      CI_JOB_NUMBER: 1
+    steps:
+      - uses: actions/checkout@v1
+      - uses: andresz1/size-limit-action@v1
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}