Add size check (#33)

Author: stramel

.github/workflows/size.yml

@@ -0,0 +1,17 @@
+name: Compressed Size
+
+on:
+  pull_request:
+    branches:
+      - '**'
+    paths:
+      - 'src/*.tsx?'
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: preactjs/compressed-size-action@v1
+        with:
+          repo-token: '${{ secrets.GITHUB_TOKEN }}'