Bump rubocop-govuk from 3.16.0 to 3.17.0

Bumps [rubocop-govuk](https://github.com/alphagov/rubocop-govuk) from 3.16.0 to 3.17.0.
- [Release notes](https://github.com/alphagov/rubocop-govuk/releases)
- [Changelog](https://github.com/alphagov/rubocop-govuk/blob/master/CHANGELOG.md)
- [Commits](alphagov/rubocop-govuk@v3.16.0...v3.17.0)

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

Author: dependabot[bot]

Gemfile.lock

@@ -128,7 +128,7 @@ GEM
     http-accept (1.7.0)
     http-cookie (1.0.3)
       domain_name (~> 0.5)
-    i18n (1.8.3)
+    i18n (1.8.4)
       concurrent-ruby (~> 1.0)
     image_size (2.0.2)
     io-like (0.3.0)
@@ -179,9 +179,9 @@ GEM
     nokogiri (1.10.10)
       mini_portile2 (~> 2.4.0)
     null_logger (0.0.1)
-    parallel (1.19.1)
-    parser (2.7.1.3)
-      ast (~> 2.4.0)
+    parallel (1.19.2)
+    parser (2.7.1.4)
+      ast (~> 2.4.1)
     phantomjs (2.1.1.0)
     plek (4.0.0)
     pry (0.13.1)
@@ -247,30 +247,30 @@ GEM
     rexml (3.2.4)
     robotex (1.0.0)
     rouge (3.21.0)
-    rubocop (0.85.1)
+    rubocop (0.87.1)
       parallel (~> 1.10)
-      parser (>= 2.7.0.1)
+      parser (>= 2.7.1.1)
       rainbow (>= 2.2.2, < 4.0)
       regexp_parser (>= 1.7)
       rexml
-      rubocop-ast (>= 0.0.3)
+      rubocop-ast (>= 0.1.0, < 1.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 1.4.0, < 2.0)
-    rubocop-ast (0.0.3)
+    rubocop-ast (0.2.0)
       parser (>= 2.7.0.1)
-    rubocop-govuk (3.16.0)
-      rubocop (= 0.85.1)
+    rubocop-govuk (3.17.0)
+      rubocop (= 0.87.1)
       rubocop-rails (= 2.6.0)
       rubocop-rake (= 0.5.1)
-      rubocop-rspec (= 1.39.0)
+      rubocop-rspec (= 1.42.0)
     rubocop-rails (2.6.0)
       activesupport (>= 4.2.0)
       rack (>= 1.1)
       rubocop (>= 0.82.0)
     rubocop-rake (0.5.1)
       rubocop
-    rubocop-rspec (1.39.0)
-      rubocop (>= 0.68.1)
+    rubocop-rspec (1.42.0)
+      rubocop (>= 0.87.0)
     ruby-progressbar (1.10.1)
     rubyzip (2.0.0)
     safe_yaml (1.0.5)