Support graphql v17

[andrew-demb]

Story

As a server author.

I want the peer range to allow graphql@17

So that I can upgrade graphql-js without --legacy-peer-deps

The range caps at 16 in package.json, and because it's a hard upper bound npm fails the install instead of warning:

graphql-http/package.json

Line 116 in 08b4ed2

"graphql": ">=0.11 <=16"

Looks like it already works. With graphql@17.0.2 + graphql-http@1.22.4 + express on Node 24, installed via --legacy-peer-deps and otherwise untouched:

• auditServer → 60/60 ok, 0 warns
• queries, throwing resolvers, validation/parse errors, introspection, graphql-response+json negotiation → same responses as v16
• types compile clean against v17's .d.ts (strict, commonjs)

Makes sense given handler.js only uses parse, validate, specifiedRules, execute, getOperationAST, GraphQLError.

Acceptance criteria

• graphql-http installs against graphql@17 without peer-dep errors
• CI runs the suite against both 16 and 17 (the graphql devDep is pinned to ^16.8.1)

Happy to PR it.