Update dependency @nestjs/graphql to v8

Editor assessment

Updating @nestjs/graphql to v8 under fix(deps) states the dependency and the major target version exactly. The fix type follows the project's renovate convention for runtime dependency refreshes — valid house style rather than a defect. A jump to v8 is where a compatibility note would have added real value, and its absence is felt, but the metadata marks nothing breaking and the subject is unambiguous. No footers appear. Hygiene is clean: imperative mood, no trailing period, precise subject, no pasted content or junk tokens.