add github action

.github/workflows/tcpdog.yml

@@ -0,0 +1,46 @@
+name: "build"
+
+on:
+  push:
+    branches:
+      - main
+    paths-ignore:
+      - "docs/**"
+      - "**.md"
+  pull_request:
+    branches:
+      - main
+    paths-ignore:
+      - "docs/**"
+      - "**.md"
+
+jobs:
+  tcpdog:
+    name: Test and build
+    runs-on: ubuntu-18.04
+    steps:
+      - name: Set up Golang
+        uses: actions/setup-go@v2
+        with:
+          go-version: ^1.15
+
+      - name: Check out code
+        uses: actions/checkout@v2
+
+      - name: Build client
+        run: |
+          cd tcpdog
+          go build
+
+      - name: Build server
+        run: |
+          cd server
+          go build
+
+      - name: Test
+        run: go test . -timeout 5m -coverprofile=profile.cov
+
+      - name: Coveralls
+        uses: shogo82148/actions-goveralls@v1
+        with:
+          path-to-profile: profile.cov