Add testing workflow

- Tests with pytest and produces coverage report
- Lints with flake8
- Tests on versions 3.7 and 3.x (latest)
  - While 3.6 is supported and tested, it is not tested automatically due to limitations in the GitHub workflows environment :(

.github/workflows/test_and_lint.yml

@@ -0,0 +1,47 @@
+# This workflow will install Python dependencies, run tests and lint with a variety of Python versions
+# For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-python
+
+name: Tests
+
+on:
+  push:
+    branches: [ "master" ]
+  pull_request:
+    branches: [ "master" ]
+
+jobs:
+  test_and_lint:
+    permissions:
+      pages: write
+      id-token: write
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+       os: [ubuntu-latest]
+       python-version: ["3.7", "3.x"]
+
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v5
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        python -m pip install flake8 pytest pytest-responses coverage genbadge defusedxml
+        if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
+        pip install .
+    - name: Lint with flake8
+      run: |
+        # stop the build if there are Python syntax errors or undefined names
+        flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
+        # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
+        flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
+    - name: Test with pytest and coverage
+      run: |      
+        coverage run -m pytest  
+        coverage report