Add Mongo for tests

.github/workflows/tests.yaml

@@ -18,6 +18,10 @@ jobs:
       uses: actions/setup-node@v1
       with:
         node-version: ${{ matrix.node-version }}
+    - name: Start MongoDB
+      uses: supercharge/mongodb-github-action@1.1.0
+      with:
+        mongodb-version: ${{ matrix.mongodb-version }}
     - name: npm install
       run: npm i
     - name: npm test