Create build.yml, resolve #10 & #13

Author: laqieer

.github/workflows/build.yml

@@ -0,0 +1,29 @@
+name: Build CI
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+    container: devkitpro/devkitarm
+
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        submodules: true
+
+    - name: Install dependencies
+      run: apt-get update && apt-get install -y build-essential && apt-get install -y python3-pip && python3 -m pip install --upgrade pip && python3 -m pip install --upgrade Pillow
+
+    - name: Build
+      run: make
+
+    - uses: actions/upload-artifact@v4
+      with:
+        name: demo
+        path: summer.gba