add workflow for test coverage

.github/workflows/main.yml

@@ -0,0 +1,30 @@
+name: Run tests and upload coverage
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  test:
+    name: Run tests and collect coverage
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Go
+        uses: actions/setup-go@v5
+
+      - name: Install dependencies
+        run: go mod download
+
+      - name: Run tests
+        run: go test -count=1 -coverprofile=coverage.txt ./...
+
+      - name: Upload results to Codecov
+        uses: codecov/codecov-action@v5
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }}
+          slug: go-spring/spring-core