Add code style workflow

.github/workflows/style.yaml

@@ -0,0 +1,25 @@
+name: Style Checks
+
+on: push
+
+jobs:
+  pep:
+    runs-on: ubuntu-latest
+
+    strategy:
+      max-parallel: 4
+      matrix:
+        python-version: [3.7]
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Install deps
+        run: |
+          pip install flake8==3.8.3
+          pip install pep8-naming==0.11.1
+          flake8 InvenTree