ci: add CI to run pure unit tests

.github/workflows/run_unit_tests.yml

@@ -0,0 +1,22 @@
+name: unit tests
+
+on:
+  push:
+    branches: [ main, dev-bfabric-2 ]
+  pull_request:
+    branches: [ main, dev-bfabric-2 ]
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Python 3.9
+        uses: actions/setup-python@v2
+        with:
+          python-version: 3.9
+      - name: Install bfabricPy
+        run: python -m pip install .
+      - name: Run unit tests
+        run: python -m unittest discover -s bfabric/tests/unit -p 'test_*.py'