Check PEP8 on CI (tardis-sn#2039)

* Add Flake8 job

* Change to file description

.github/workflows/codestyle.yml

@@ -0,0 +1,48 @@
+#  For more information about TARDIS pipelines, please refer to:
+#
+#    https://tardis-sn.github.io/tardis/development/continuous_integration.html
+
+name: codestyle
+
+on:
+  push:
+    branches:
+    - '*'
+
+  pull_request:
+    branches:
+    - '*'
+
+jobs:
+  black:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Setup Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: 3.x
+
+      - name: Install Black
+        run: pip install black==22.3
+
+      - name: Run Black
+        run: black --check tardis
+
+  flake8:
+    if: false
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Setup Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: 3.x
+
+      - name: Install Flake8
+        run: pip install flake8==4.0.1 pep8-naming==0.12.1
+
+      - name: Run Flake8
+        run: flake8 tardis