Adds GitHub Action to run mypy on Hatchet in CI

.github/workflows/type-checking.yaml

@@ -0,0 +1,47 @@
+name: Run mypy-based type checking
+
+on:
+  push:
+    branches: [ develop ]
+  pull_request:
+    branches: [ develop, releases/** ]
+
+jobs:
+
+  type_check:
+
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        # TODO: add macos-latest
+        # TODO: change ubuntu-20.04 back to ubuntu-latest when the following issue is resolved:
+        #       https://github.com/actions/setup-python/issues/162
+        os: [ubuntu-20.04]
+        # TODO: add pypy2, pypy3
+        python-version: [3.7, 3.8, 3.9, "3.10", "3.11"]
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v5
+      with:
+        python-version: ${{ matrix.python-version }}
+
+    - name: Install Python3 dependencies
+      run: |
+        python -m pip install --upgrade pip pytest
+        pip install -r requirements.txt
+        # Optional Dependency for HDF Checkpointing
+        pip install tables
+        python setup.py install
+        python setup.py build_ext --inplace
+        python -m pip list
+        
+    - name: Install mypy
+      run: |
+        python3 -m pip install mypy==1.4.1
+        
+    - name: Run mypy
+      run: |
+        mypy hatchet --pretty