Add pytest with GitHub Action workflow

.github/workflows/test.yaml

@@ -0,0 +1,40 @@
+name: Pytest
+
+on: [pull_request]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+
+      - name: Set up python
+        id: setup-python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12.7"
+
+      - name: Install Poetry
+        uses: snok/install-poetry@v1
+        with:
+          version: 1.8.4
+          virtualenvs-create: true
+          virtualenvs-in-project: true
+
+      - name: Load cached venv
+        id: cached-pip-wheels
+        uses: actions/cache@v4
+        with:
+          path: ~/.cache
+          key: venv-${{ steps.setup-python.outputs.python-version }}-${{ hashFiles('**/poetry.lock') }}
+
+      - name: Install dependencies
+        run: cd backend && poetry install --no-interaction --no-root
+
+      - name: Install library
+        run: cd backend && poetry install --no-interaction
+
+      - run: |
+          source $VENV
+          pytest --version