ci: add build workflow for GitHub Actions

Author: chadowo

.github/workflows/build.yml

@@ -0,0 +1,19 @@
+name: Build
+
+on: [push]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Install dependencies
+        run: sudo apt update && sudo apt install mruby
+
+      - name: Configure CMake
+        run: cmake -S . -B build
+
+      - name: Build
+        run: cmake --build build