This updates to the next major release of
@graphql-eslint/eslint-plugin@3.0.0. This also updates to
graphql@15.7.2, since a transitive dependency of the linter requires it:

    @graphql-eslint/eslint-plugin
    -> graphql-config
    -> @graphql-tools/url-loader
    -> subscriptions-transport-ws
    -> graphql@^15.7.2 || ^16.0.0"