Re-add basic CI with GH actions

Signed-off-by: Mikolaj Pawlikowski <mikolaj@pawlikowski.pl>

.github/workflows/main.yml

@@ -0,0 +1,24 @@
+name: CI
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: 1.16
+      - name: Compile the binary
+        run: |
+          make bin/goldpinger
+          ./bin/goldpinger -h
+      - name: Build the Docker image
+        run: |
+          make build