Bump uglifier from 4.1.17 to 4.1.18

Bumps [uglifier](https://github.com/lautis/uglifier) from 4.1.17 to 4.1.18.
- [Release notes](https://github.com/lautis/uglifier/releases)
- [Changelog](https://github.com/lautis/uglifier/blob/master/CHANGELOG.md)
- [Commits](lautis/uglifier@v4.1.17...v4.1.18)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot-support

Gemfile.lock

@@ -319,7 +319,7 @@ GEM
     tilt (2.0.8)
     tzinfo (1.2.5)
       thread_safe (~> 0.1)
-    uglifier (4.1.17)
+    uglifier (4.1.18)
       execjs (>= 0.3.0, < 3)
     unf (0.1.4)
       unf_ext