Setup continuous integration using GitHub Actions

Run tests (pytest) and linter (black) in the CI.

The main problem is that GitHub Actions runners don't have a terminal
which is necessary for ncurses. This can be "hacked" by using the
'script' command which creates a pseudo-terminal. Also, ncurses requires
the TERM env variable to be set.

For now, we only test for Python 3.10, can add more versions in future.

.github/workflows/ci.yml

@@ -0,0 +1,34 @@
+name: Continuous Integration
+
+on: [push, pull_request]
+
+jobs:
+  build-test:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        python-version: ["3.10"]
+
+
+    steps:
+      - uses: actions/checkout@v3
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v4
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install .[test]
+      - name: Build Docker image for tests
+        run: docker build -t test example/
+      - name: Run tests
+        run: |
+          export TERM=xterm-256color && script -e -c "pytest -v"
+
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: psf/black@stable