Add initial testing script.

.github/workflows/abc_atlas_access_ci.yaml

@@ -0,0 +1,25 @@
+name: ci/ab_atlas_access
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+jobs:
+  name: ${{ matrix.python-version }}, ${{ matrix.os }}
+  runs-on: ${{ matrix.os }}
+  strategy:
+    matrix:
+      os: [ "macos-latest", "windows-latest", "ubuntu-latest" ]
+      python-version: [ "3.8", "3.9", "3.10", "3.11" ]
+    fail-fast: false
+  steps:
+    - uses: actions/checkout@v4
+    - uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+    - name: Install
+        run: |
+            python -m pip install --upgrade pip
+            pip install .
+    - name: Test
+        run: pytest tests