Add GitHub Action to find Python syntax errors

GitHub Actions will need to be enabled at https://github.com/dragen1860/Deep-Learning-with-PyTorch-Tutorials/actions

.github/workflows/pythonapp.yml

@@ -0,0 +1,25 @@
+name: Python application
+on: [push, pull_request]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v1
+    - name: Set up Python 3
+      uses: actions/setup-python@v1
+      with:
+        python-version: 3.x
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install flake8 pytest
+        pip install -r requirements.txt || true
+    - 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
+      run: |
+        pytest || true