chore: Add mypy github action

Author: TrevorBergeron

.github/sync-repo-settings.yaml

@@ -12,6 +12,7 @@ branchProtectionRules:
     - 'cla/google'
     - 'docs'
     - 'lint'
+    - 'mypy'
     - 'unit (3.9)'
     - 'unit (3.10)'
     - 'unit (3.11)'

.github/workflows/mypy.yml

@@ -0,0 +1,22 @@
+on:
+  pull_request:
+    branches:
+      - main
+name: mypy
+jobs:
+  mypy:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+    - name: Setup Python
+      uses: actions/setup-python@v5
+      with:
+        python-version: "3.10"
+    - name: Install nox
+      run: |
+        python -m pip install --upgrade setuptools pip wheel
+        python -m pip install nox
+    - name: Run mypy
+      run: |
+        nox -s mypy