Bumps [webpacker](https://github.com/rails/webpacker) from 3.5.5 to 4.0.2.
- [Release notes](https://github.com/rails/webpacker/releases)
- [Changelog](https://github.com/rails/webpacker/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rails/webpacker/compare/v3.5.5...v4.0.2)

Signed-off-by: dependabot[bot] <support@dependabot.com>
Co-authored-by: Yamagishi Kazutoshi <ykzts@desire.sh>

* Fix form validation flash message color and input borders

* Fix typo

Fix #8685

* Add separate setting for sidebar text (site_short_description)

* Fix tests

* Add follow button to detailed status, add gradient to mask bio cut-off

* In landing strip, show sign up link even if closed (different href)

Point to joinmastodon.org

Follow-up to #6124

* Redesign public profiles

* Responsive design

* Change public profile status filtering defaults and add options

- No longer displays private/direct toots even if you are permitted access
- By default omits replies
- "With replies" option
- "Media only" option

* Redesign account grid cards

* Fix style issues

* Add link for domain in land strip

* Use root_path

* Avoid repeating code

* Move site title helper to instance helper (name change only)

* Remove newline in <title> tag

* Add site_hostname helper method to wrap up local_domain value

* Use site_hostname helper in places that need local_domain value

* Add missing emojify class to landing strip

* Add missing emojify class to simple_status partial