Add github workflow test

.github/workflows/style_test.yml

@@ -0,0 +1,21 @@
+name: style_test
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Python 3.8
+      uses: actions/setup-python@v1
+      with:
+        python-version: 3.8
+    - name: Install dependencies
+      run: |
+        sudo apt install gir1.2-gtk-3.0 libgirepository1.0-dev libapt-pkg-dev fakeroot
+        python -m pip install --upgrade pip
+        pip install -r requirements.txt
+    - name: Test with pytest
+      run: |
+        ./runtests pep8