[appsync-emulator-serverless] Conflicting peer dependencies

[vicary]

I'm being directed here from aheissenberger/serverless-appsync-offline#31, copying the original issue description below.

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The current version of serverless-appsync-offline has indirect dependencies that conflicts in their peer dependencies of graphql. npm install output extracted below,

npm WARN graphql-subscriptions@0.5.8 requires a peer of graphql@^0.10.5 || ^0.11.3 || ^0.12.0 || ^0.13.0 but none is installed. You must install peer dependencies yourself.
npm WARN graphql-tools@3.1.1 requires a peer of graphql@^0.13.0 but none is installed. You must install peer dependencies yourself.
npm WARN apollo-link-http@1.3.1 requires a peer of graphql@^0.11.0 but none is installed. You must install peer dependencies yourself

I suggest updating graphql-* packages to at least those versions that depends on graphql@14.x for long term stability.