CI: add Gitea-compatible workflow wrapper

.gitea/workflows/ci.yml

@@ -0,0 +1,18 @@
+name: CI
+on:
+  push:
+    branches: [ main, work/review ]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Set up Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: '1.20'
+      - name: Build
+        run: make build
+      - name: Test
+        run: make test