add Build examples step to CI

.github/workflows/pull_request.yaml

@@ -23,3 +23,20 @@ jobs:
         shell: bash
         run: |
           PATH=$PWD/misc/wasm:$PATH GOOS=js GOARCH=wasm go test ./...
+
+  examples:
+    name: Build examples
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+
+      - name: Setup Golang
+        uses: actions/setup-go@v4
+        with:
+          go-version: ${{ matrix.go-version }}
+
+      - name: Build examples
+        shell: bash
+        run: make build-examples
+