`graphql` on peerDependencies should be >=15?

[robertu7]

As title, graphql@15 was in devDependencies but graphql@14 in peerDependencies, it makes npm install fails with ERESOLVE unable to resolve dependency tree error.

[fmoga]

I'm affected by this too

[tony]

Created a PR at #61. Looking good so far

However, I'm not sure if GraphQL 14 will still work. In fact, it may be more convenient to deprecate it and keep graphql-14 bug fixes in a branch, e.g. start 1.6. Though it's up to @dangcuuson

You can test it at @peergrade/graphql-schema-typescript