Bump rubocop-govuk from 3.15.0 to 3.16.0

Bumps [rubocop-govuk](https://github.com/alphagov/rubocop-govuk) from 3.15.0 to 3.16.0.
- [Release notes](https://github.com/alphagov/rubocop-govuk/releases)
- [Changelog](https://github.com/alphagov/rubocop-govuk/blob/master/CHANGELOG.md)
- [Commits](alphagov/rubocop-govuk@v3.15.0...v3.16.0)

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

Gemfile.lock

@@ -226,7 +226,7 @@ GEM
     rb-inotify (0.10.1)
       ffi (~> 1.0)
     redis (4.2.0)
-    regexp_parser (1.7.0)
+    regexp_parser (1.7.1)
     request_store (1.5.0)
       rack (>= 1.4)
     rest-client (2.1.0)
@@ -236,7 +236,7 @@ GEM
       netrc (~> 0.8)
     rexml (3.2.4)
     rouge (3.19.0)
-    rubocop (0.85.0)
+    rubocop (0.85.1)
       parallel (~> 1.10)
       parser (>= 2.7.0.1)
       rainbow (>= 2.2.2, < 4.0)
@@ -247,15 +247,15 @@ GEM
       unicode-display_width (>= 1.4.0, < 2.0)
     rubocop-ast (0.0.3)
       parser (>= 2.7.0.1)
-    rubocop-govuk (3.15.0)
-      rubocop (= 0.85.0)
-      rubocop-rails (~> 2)
-      rubocop-rake (~> 0.5.1)
-      rubocop-rspec (~> 1.28)
-    rubocop-rails (2.5.2)
-      activesupport
+    rubocop-govuk (3.16.0)
+      rubocop (= 0.85.1)
+      rubocop-rails (= 2.6.0)
+      rubocop-rake (= 0.5.1)
+      rubocop-rspec (= 1.39.0)
+    rubocop-rails (2.6.0)
+      activesupport (>= 4.2.0)
       rack (>= 1.1)
-      rubocop (>= 0.72.0)
+      rubocop (>= 0.82.0)
     rubocop-rake (0.5.1)
       rubocop
     rubocop-rspec (1.39.0)