Resolve peer dependency errors due to eslint upgrade

Now that NPM 7 tries to install peer dependencies, having an old version
of these packages alongside a newer version of eslint will not work with
`npm install` as it used to.

These are the earliest versions that support the installed eslint
version.

Commands used¹:

    npm info eslint-config-airbnb@18 peerDependencies
    npm info eslint-plugin-jsx-a11y@6 peerDependencies
    npm info eslint-plugin-react-hooks@4 peerDependencies

    npm install \
        eslint-config-airbnb@18.2.0 \
        eslint-plugin-jsx-a11y@6.3.0 \
        eslint-plugin-react-hooks@4.0.1