Bump govuk_publishing_components from 16.16.0 to 16.18.0

Bumps [govuk_publishing_components](https://github.com/alphagov/govuk_publishing_components) from 16.16.0 to 16.18.0.
- [Release notes](https://github.com/alphagov/govuk_publishing_components/releases)
- [Changelog](https://github.com/alphagov/govuk_publishing_components/blob/master/CHANGELOG.md)
- [Commits](alphagov/govuk_publishing_components@v16.16.0...v16.18.0)

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

Gemfile

@@ -17,7 +17,7 @@ gem 'gds-api-adapters', '~> 59.2'
 gem 'govuk_ab_testing', '~> 2.4'
 gem 'govuk_app_config', '~> 1.16'
 gem 'govuk_frontend_toolkit', '~> 8.2.0'
-gem 'govuk_publishing_components', '~> 16.16.0'
+gem 'govuk_publishing_components', '~> 16.18.0'
 gem 'plek', '~> 2.1'
 gem 'slimmer', '~> 13.1'
 

Gemfile.lock

@@ -118,7 +118,7 @@ GEM
     govuk_frontend_toolkit (8.2.0)
       railties (>= 3.1.0)
       sass (>= 3.2.0)
-    govuk_publishing_components (16.16.0)
+    govuk_publishing_components (16.18.0)
       gds-api-adapters
       govuk_app_config
       govuk_frontend_toolkit
@@ -127,7 +127,7 @@ GEM
       rails (>= 5.0.0.1)
       rake
       rouge
-      sass-rails (>= 5.0.4)
+      sassc-rails (>= 2.0.1)
     govuk_schemas (3.2.0)
       json-schema (~> 2.8.0)
     hashdiff (0.3.7)
@@ -181,7 +181,7 @@ GEM
       ruby-progressbar
     mocha (1.8.0)
       metaclass (~> 0.0.1)
-    multipart-post (2.1.0)
+    multipart-post (2.1.1)
     netrc (0.11.0)
     nio4r (2.3.1)
     nokogiri (1.10.3)
@@ -279,6 +279,15 @@ GEM
       sprockets (>= 2.8, < 4.0)
       sprockets-rails (>= 2.0, < 4.0)
       tilt (>= 1.1, < 3)
+    sassc (2.0.1)
+      ffi (~> 1.9)
+      rake
+    sassc-rails (2.1.1)
+      railties (>= 4.0.0)
+      sassc (>= 2.0)
+      sprockets (> 3.0)
+      sprockets-rails
+      tilt
     scss_lint (0.58.0)
       rake (>= 0.9, < 13)
       sass (~> 3.5, >= 3.5.5)
@@ -354,7 +363,7 @@ DEPENDENCIES
   govuk_ab_testing (~> 2.4)
   govuk_app_config (~> 1.16)
   govuk_frontend_toolkit (~> 8.2.0)
-  govuk_publishing_components (~> 16.16.0)
+  govuk_publishing_components (~> 16.18.0)
   govuk_schemas (~> 3.2)
   htmlentities (~> 4.3)
   jasmine-rails