add unit tests workflow

.github/workflows/unit_tests.yml

@@ -0,0 +1,30 @@
+name: python_unit_tests
+
+on:
+  push:
+    paths:
+      - '**/*.py'
+  pull_request:
+    paths:
+      - '**/*.py'
+
+jobs:
+  unit-tests:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r tubearchivist/requirements-dev.txt
+
+      - name: Run unit tests
+        run: pytest tubearchivist