Log Message:
luakit: Update to 2.3

## [2.3]

### Added

- Added Gopher protocol support, see comment in rc.lua.
- Added two commands to clear website data (:clear-data, :clear-favicon-db).
- Added dark mode support setting `application.prefer_dark_mode`.
- The tabmenu plugin is now included in luakit (:tabmenu).

### Changed

- Removed debug symbol generation for default make.
- Changed the C standard from gnu99 to c11 because Webkit wants it.
- The proxy module remembers when no proxy or system proxy was used last.
- The proxy widget is hidden when proxy "None" is active.

### Fixed

- Fixed bounding box not spanning over whole element.
- Fixed an issue where styled hint labels caused intransparent bounding boxes.
- Fixed a race condition when a tab is closed on NetBSD.
- Do not execute "git ls-files" when luakit is not a git repository

### Update information

- The gopher module needs `luasocket` installed.