chore: update to eslint 9; update devDeps.

[brettz9]

Hi,

This updates to ESLint 9, following the same basic linting expectations. It changes from "standard" to "neostandard" given the defunct state of the former and its lack of ESLint 9 support.

I've also updated some other devDeps.

Let me know if you are interested in a PR for an explicit type: module in package.json.

[marijnh]

Thanks! Merged as ddba1e4, and followed up with 9e12432 to suppress this warning:

(node:179089) [MODULE_TYPELESS_PACKAGE_JSON] Warning: Module type of file:///home/marijn/src/acorn/eslint.config.js?mtime=1761900903845 is not specified and it doesn't parse as CommonJS.