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/postgres.yml

@@ -0,0 +1,57 @@
+---
+name: CTFd Postgres CI
+
+on: [pull_request]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+    services:
+      postgres:
+        image: postgres
+        ports:
+          - 5432:5432
+        env:
+          POSTGRES_HOST_AUTH_METHOD: trust
+          POSTGRES_DB: ctfd
+        # Set health checks to wait until postgres has started
+        options: >-
+          --health-cmd pg_isready
+          --health-interval 10s
+          --health-timeout 5s
+          --health-retries 5
+      redis:
+        image: redis
+        ports:
+          - 6379:6379
+
+    strategy:
+      matrix:
+        python-version: ['3.6']
+        TESTING_DATABASE_URL: ['postgres://postgres@localhost/ctfd']
+
+    name: Python ${{ matrix.python-version }}
+    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
+
+      - name: Test
+        run: |
+            sudo rm -f /etc/boto.cfg
+            make test
+        env:
+            AWS_ACCESS_KEY_ID: AKIAIOSFODNN7EXAMPLE
+            AWS_SECRET_ACCESS_KEY: wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY
+
+      - name: Coverage
+        run: codecov
+