ci: add python 3.15 and run lint and tests from one workflow

.github/workflows/ci.yml

@@ -0,0 +1,50 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - uses: actions/checkout@v7
+      - name: Set up Python
+        uses: actions/setup-python@v7
+        with:
+          python-version: "3.15"
+      - name: Install dependencies
+        run: |
+          pip install -U pip
+          pip install .
+      - name: Lint and check formatting
+        run: |
+          ruff check .
+          ruff format --check .
+  test:
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    strategy:
+      matrix:
+        python-version:
+          - "3.11"
+          - "3.12"
+          - "3.13"
+          - "3.14"
+          - "3.15"
+    steps:
+      - uses: actions/checkout@v7
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v7
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Install dependencies
+        run: |
+          pip install -U pip
+          pip install .
+      - name: Run all tests
+        run: |
+          pytest . -v