Add simple CI check.

.github/workflows/ci.yml

@@ -0,0 +1,32 @@
+name: ci
+
+on:
+  push:
+    branches: [ "develop", "master" ]
+  pull_request:
+    branches: [ "develop", "master" ]
+
+permissions:
+  contents: read
+
+jobs:
+
+  # Run all tests.
+  base-ci:
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+
+    steps:
+    - uses: actions/checkout@v3
+
+    - uses: actions/setup-python@v4
+      with:
+        python-version: 3.11
+        cache: 'pip' # caching pip dependencies
+
+    - run: pip install -r requirements.txt
+
+    - name: Test
+      run: |
+        set -e
+        python verify_files.py