Bump govuk_tech_docs from 2.4.1 to 3.0.0

Bumps [govuk_tech_docs](https://github.com/alphagov/tech-docs-gem) from 2.4.1 to 3.0.0:
  - [Release notes](https://github.com/alphagov/tech-docs-gem/releases/tag/v3.0.0)
  - [Changelog](https://github.com/alphagov/tech-docs-gem/blob/master/CHANGELOG.md)
  - [Commits](alphagov/tech-docs-gem@v2.4.1...v3.0.0)

Major version bump includes breaking changes to search user experience.

Gemfile.lock

@@ -1,7 +1,7 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (6.1.4)
+    activesupport (6.1.4.1)
       concurrent-ruby (~> 1.0, >= 1.0.2)
       i18n (>= 1.6, < 2)
       minitest (>= 5.1)
@@ -10,16 +10,16 @@ GEM
     addressable (2.8.0)
       public_suffix (>= 2.0.2, < 5.0)
     ast (2.4.2)
-    autoprefixer-rails (10.2.5.1)
-      execjs (> 0)
+    autoprefixer-rails (10.3.3.0)
+      execjs (~> 2)
     backports (3.21.0)
     chronic (0.10.2)
     chunky_png (1.4.0)
     coffee-script (2.4.1)
       coffee-script-source
       execjs
     coffee-script-source (1.12.2)
-    commonmarker (0.22.0)
+    commonmarker (0.23.2)
     compass (1.0.3)
       chunky_png (~> 1.2)
       compass-core (~> 1.0.2)
@@ -42,10 +42,10 @@ GEM
     erubis (2.7.0)
     eventmachine (1.2.7)
     execjs (2.8.1)
-    fast_blank (1.0.0)
-    fastimage (2.2.4)
-    ffi (1.15.3)
-    govuk_tech_docs (2.4.1)
+    fast_blank (1.0.1)
+    fastimage (2.2.5)
+    ffi (1.15.4)
+    govuk_tech_docs (3.0.0)
       autoprefixer-rails (~> 10.2)
       chronic (~> 0.10.2)
       middleman (~> 4.0)
@@ -143,7 +143,7 @@ GEM
       padrino-support (= 0.15.1)
       tilt (>= 1.4.1, < 3)
     padrino-support (0.15.1)
-    parallel (1.20.1)
+    parallel (1.21.0)
     parser (3.0.0.0)
       ast (~> 2.4.1)
     parslet (2.0.0)
@@ -160,7 +160,7 @@ GEM
       ffi (~> 1.0)
     redcarpet (3.5.1)
     rexml (3.2.5)
-    rouge (3.26.0)
+    rouge (3.26.1)
     rspec (3.7.0)
       rspec-core (~> 3.7.0)
       rspec-expectations (~> 3.7.0)