Add coverage workflow

Author: nao1215

.github/workflows/coverage.yml

@@ -0,0 +1,26 @@
+on: [pull_request]
+name: Coverage
+jobs:
+  test:
+    strategy:
+      matrix:
+        go-version: [1.19.x]
+        os: [ubuntu-latest]
+
+    runs-on: ${{ matrix.os }}
+    steps:
+      - name: Install Go
+        uses: actions/setup-go@v3
+        with:
+          go-version: ${{ matrix.go-version }}
+
+      - name: Checkout code
+        uses: actions/checkout@v3
+
+      - name: Test
+        run: go test -race -coverprofile="coverage.txt" -covermode=atomic ./...
+
+      - name: upload coverage
+        uses: codecov/codecov-action@v1
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }}