Fix coverage

.github/workflows/static.yml

+name: static
+
+on:
+  push:
+    branches: ['master']
+  workflow_dispatch:
+
+# Set permissions of the GITHUB_TOKEN to allow deployment to GitHub Pages.
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+concurrency:
+  group: pages
+  cancel-in-progress: true
+
+jobs:
+  deploy:
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Setup Pages
+        uses: actions/configure-pages@v5
+      - name: Generate coverage and badge
+        run: |
+          ./ci/test.sh
+          mkdir -p ./ci/out/static
+          cp ./ci/out/coverage.html ./ci/out/static/coverage.html
+          percent=$(go tool cover -func ./ci/out/coverage.prof | tail -n1 | awk '{print $3}' | tr -d '%')
+          wget -O ./ci/out/static/coverage.svg "https://img.shields.io/badge/coverage-${percent}%25-success"
+      - name: Upload artifact
+        uses: actions/upload-pages-artifact@v3
+        with:
+          path: ./ci/out/static/
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@v4

README.md

 # websocket
 
 [![Go Reference](https://pkg.go.dev/badge/github.com/coder/websocket.svg)](https://pkg.go.dev/github.com/coder/websocket)
-[![Go Coverage](https://img.shields.io/badge/coverage-91%25-success)](https://github.com/coder/websocket/coverage.html)
+[![Go Coverage](https://coder.github.io/websocket/coverage.svg)](https://coder.github.io/websocket/coverage.html)
 
 websocket is a minimal and idiomatic WebSocket library for Go.