Remove unused filter-obj dependency

[HeversonSilva-gif]

Which problem is this pull request solving?

filter-obj is listed in dependencies but nothing in the package uses it, so every
install resolves and downloads it for nothing.

List other issues or pull requests related to this problem

No existing issue. The same leftover declaration is in all-node-versions (ehmicky/all-node-versions#45) and
node-version-alias (ehmicky/node-version-alias#44), where I have opened the same change. Since these three depend
on one another, filter-obj only leaves a consumer's tree once all three are merged.

Describe the solution you've chosen

Removed the filter-obj entry from dependencies and let npm install update
package-lock.json. No source file changed.

The only import was import { excludeKeys } from 'filter-obj' in src/options.js. That
file was deleted in b1b5de9 ("Reduce npm package size", 2022-10-16), and the dependency
declaration stayed behind.

Verified at dd5aab5 on Node 20.20.0:

• git grep filter-obj matches package.json and package-lock.json and nothing else.
  Searching for filterObj and filter_obj finds nothing, so it is not imported under
  another name.
• npm test before the change: 9 tests passed, exit 0.
• npm test after the change: 9 tests passed, exit 0.

npm test runs prettier, eslint, jscpd and the type check in the same task, so those ran
on both sides as well.

Describe alternatives you've considered

Moving it to devDependencies. Nothing references it there either, including the tests,
so there is nothing to keep it for.

Checklist

• I have read the contribution guidelines.
• I have added tests (we are enforcing 100% test coverage). No code was added or
  changed, so there is nothing new to cover and coverage is unaffected.
• I have added documentation in the README.md, the docs directory (if any). Not
  applicable: no API, option or behaviour change.
• The status checks are successful (continuous integration). I cannot tick this before
  opening the pull request; I will confirm once CI has run.

[ehmicky]

Thanks a lot, this looks good!

[ehmicky]

@all-contributors Please add @HeversonSilva-gif for code.

[allcontributors]

@ehmicky

I've put up a pull request to add @HeversonSilva-gif! 🎉