Seperate out postgres tests and clarify postgres support (#1494)

* Clarifies the position on supporting Postgres and removes Postgres from the main test suite
* Closes #973

.github/workflows/lint.yml

@@ -0,0 +1,33 @@
+---
+name: Linting
+
+on: [push]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        python-version: ['3.6']
+        TESTING_DATABASE_URL: ['sqlite://']
+
+    name: Linting
+    steps:
+      - uses: actions/checkout@v2
+      - name: Setup python
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+          architecture: x64
+      - name: Install dependencies
+        run: |
+            python -m pip install --upgrade pip
+            python -m pip install -r development.txt
+            sudo yarn install --non-interactive
+            sudo yarn global add prettier@1.17.0
+
+      - name: Lint
+        run: make lint
+