Update dependency fast-json-stringify to v2.5.4

Editor assessment

A minimal Renovate update, correctly typed — if fast-json-stringify v2.5.4 fixed a real defect, `fix(deps)` is earned; otherwise it is a routine patch many repos would log as `chore(deps)`. The subject `update dependency fast-json-stringify to v2.5.4` hits every subject rule: imperative, lowercase, no trailing period, about 48 characters, package and target version both named. The `deps` scope aids grouping. With no body and no linked issue, reviewers must consult the upstream changelog themselves, which is tolerable for maintenance commits. Not breaking; patch inference is unambiguous. A clean, if bare, example of the form.