fix: correctly specify return type of CANCEL_SYMBOL - #601

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: ljharb/require-allow-edits@be4a9d13001dfa5bfc10af68313bad753d7bdc6a. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/