Bump uglifier from 3.2.0 to 4.1.9

Bumps [uglifier](https://github.com/lautis/uglifier) from 3.2.0 to 4.1.9.
- [Release notes](https://github.com/lautis/uglifier/releases)
- [Changelog](https://github.com/lautis/uglifier/blob/master/CHANGELOG.md)
- [Commits](lautis/uglifier@v3.2.0...v4.1.9)

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

Gemfile.lock

@@ -667,7 +667,7 @@ GEM
       ethon (>= 0.8.0)
     tzinfo (1.2.4)
       thread_safe (~> 0.1)
-    uglifier (3.2.0)
+    uglifier (4.1.9)
       execjs (>= 0.3.0, < 3)
     unf (0.1.4)
       unf_ext