Merge pull request #1395 from alphagov/dependabot/bundler/terser-1.2.6

Author: govuk-ci

Gemfile.lock

@@ -725,7 +725,7 @@ GEM
       sprockets (>= 3.0.0)
     statsd-ruby (1.5.0)
     stringio (3.1.7)
-    terser (1.2.5)
+    terser (1.2.6)
       execjs (>= 0.3.0, < 3)
     thor (1.3.2)
     timeout (0.4.3)