ci: add a job that check the typing

Author: autra

.github/workflows/mypy.yml

@@ -0,0 +1,30 @@
+name: Typing Check
+
+on:
+  push:
+    paths:
+      - '**.py'
+  pull_request:
+    paths:
+      - '**.py'
+
+jobs:
+  mypy:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.10'  # oldest supported python version
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install .[dev]
+
+      - name: Run mypy
+        run: mypy

setup.py

@@ -42,6 +42,7 @@ def _read_requirements(filename):
         packages=setuptools.find_packages(),
         package_data={"fastapi_cloudevents": ["py.typed"]},
         install_requires=_read_requirements("requirements.txt"),
+        extras_require={"dev": ["mypy"]},
         classifiers=[
             "Intended Audience :: Information Technology",
             "Intended Audience :: System Administrators",