Bump uglifier from 4.1.20 to 4.2.0

Bumps [uglifier](https://github.com/lautis/uglifier) from 4.1.20 to 4.2.0.
- [Release notes](https://github.com/lautis/uglifier/releases)
- [Changelog](https://github.com/lautis/uglifier/blob/master/CHANGELOG.md)
- [Commits](https://github.com/lautis/uglifier/commits)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Gemfile.lock

@@ -169,7 +169,7 @@ GEM
     turbolinks-source (5.2.0)
     tzinfo (1.2.5)
       thread_safe (~> 0.1)
-    uglifier (4.1.20)
+    uglifier (4.2.0)
       execjs (>= 0.3.0, < 3)
     unicode-display_width (1.5.0)
     web-console (3.7.0)