Remove graphql as peer dependency

[MasterOdin]

PR removes graphql as a peer dependency from this module. graphql is not used directly within this module, so having it as a peer dependency doesn't really make much sense, and it's already a peer dependency for @apollo/client (which does actively need it) so from an end-user's perspective, they'll still be appropriately warned if they're missing it, granted it'll be one level more nested in the warning.

This resolves the issue for us where we get a peer dependency warning that next-apollo does not support graphql@^16.0.0 and while could add that version here, it's effectively meaningless since it's really what @apollo/client supports and not this library.