`apollo-server` out of date in graphql-node tutorial

[TasinIshmam]

Problem

The graphql-node tutorial currently uses version 2 of apollo-server. However with the release of apollo-sever version 3, certain components of the tutorial no longer work properly.

A list of non-exhaustive breaking changes

• apollo-server v3 no longer uses graphql-playground by default.
• apollo-server v3 does not support subscription out of the box.

Proposed Solution

• Upgrade the tutorial to use the latest version of apollo-sever, fixing all breaking changes as suggested in the migration docs of apollo server 3.

Temporary quick-fix/workaround

• Pin apollo server to version 2 in the tutorial, so people do not accidentally install the latest version and break the tutorial.

Related Issues

• Real time subscription chapter for graphql-node tutorial needs update #1349