Bump terser from 1.2.0 to 1.2.1

Bumps [terser](https://github.com/ahorek/terser-ruby) from 1.2.0 to 1.2.1.
- [Release notes](https://github.com/ahorek/terser-ruby/releases)
- [Changelog](https://github.com/ahorek/terser-ruby/blob/master/CHANGELOG.md)
- [Commits](https://github.com/ahorek/terser-ruby/compare/1.2.0...1.2.1)

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

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

Gemfile.lock

@@ -516,7 +516,7 @@ GEM
     stringio (3.1.0)
     telegraf (3.0.0)
     temple (0.10.3)
-    terser (1.2.0)
+    terser (1.2.1)
       execjs (>= 0.3.0, < 3)
     thor (1.3.1)
     tilt (2.3.0)