Add build.yml workflow

.github/workflows/build.yml

@@ -0,0 +1,20 @@
+name: Build
+
+on:
+  push:
+    branches: main
+  pull_request:
+    branches: main
+
+jobs:
+  build:
+    strategy:
+      fail-fast: false
+    runs-on: ubuntu-latest
+    env:
+      # allow opam depext to yes package manager prompts
+      OPAMCONFIRMLEVEL: unsafe-yes
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+