Updated expressGraphQL to graphqlHTTP

[akshatatray]

Before : const expressGraphQL = require("express-graphql");

After : const { graphqlHTTP } = require("express-graphql");

This is the correct way, as described in the documentation.

const expressGraphQL gave errors

[BarrBrian]

@WebDevSimplified - please consider this PR and consider putting a note on your video.

I believe the syntax may have changed since your original recording and this seems to be tripping many people up.