Add Github Actions regression tests

.github/workflows/regression-tests.yml

@@ -0,0 +1,33 @@
+name: Regression Tests
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    name: Python ${{matrix.python-version}}
+    runs-on: ubuntu-20.04
+    
+    strategy:
+      matrix:
+        python-version: [3.9]
+        group: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
+
+    steps:
+    - uses: actions/checkout@v1
+
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v2
+      with:
+        python-version: ${{ matrix.python-version }}
+
+    - name: Install Icarus Verilog
+      run: |
+        sudo apt install -y --no-install-recommends iverilog
+
+    - name: Install Python dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install tox tox-gh-actions
+
+    - name: Test with tox
+      run: tox -- --splits 20 --group ${{ matrix.group }}