Bump terser from 1.1.18 to 1.1.19

Bumps [terser](https://github.com/ahorek/terser-ruby) from 1.1.18 to 1.1.19.
- [Release notes](https://github.com/ahorek/terser-ruby/releases)
- [Changelog](https://github.com/ahorek/terser-ruby/blob/master/CHANGELOG.md)
- [Commits](ahorek/terser-ruby@1.1.18...1.1.19)

---
updated-dependencies:
- dependency-name: terser
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Gemfile.lock

@@ -474,7 +474,7 @@ GEM
     telegraf (2.1.1)
       influxdb
     temple (0.10.3)
-    terser (1.1.18)
+    terser (1.1.19)
       execjs (>= 0.3.0, < 3)
     thor (1.2.2)
     tilt (2.3.0)