tests: started work on GitHub workflow

FossilOrigin-Name: c038bdea612b3d98b605579b7733283d2c22dd63cbcfcb38bf4be9ef88f22566

Author: thindil

.github/workflows/nim.yml

@@ -0,0 +1,31 @@
+name: Continuous Integration
+
+on:
+  push:
+    branches: [ trunk ]
+
+jobs:
+
+  tests:
+    timeout-minutes: 30
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+
+    - name: Setup Nim
+      uses: jiro4989/setup-nim-action@v2
+      with:
+        nim-version: 'stable'
+        repo-token: ${{ secrets.GITHUB_TOKEN }}
+
+    - name: Update Nimble
+      run: nimble install -y nimble
+
+    - name: Debug demo build
+      run: |
+        sudo apt-get install -y libsdl2-dev
+        cd demo
+        ./build.nims sdl2
+