Update dependencies

Main one is govuk-tech-docs gem v2.4.3 which brings

- [#236: Fix search 'autocomplete' behaviour](alphagov/tech-docs-gem#236)
- [#203: Update vendored javascripts](alphagov/tech-docs-gem#203)

Gemfile.lock

@@ -10,24 +10,24 @@ GIT
 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)
       tzinfo (~> 2.0)
       zeitwerk (~> 2.3)
     addressable (2.8.0)
       public_suffix (>= 2.0.2, < 5.0)
-    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 (0.23.1)
     compass (1.0.3)
       chunky_png (~> 1.2)
       compass-core (~> 1.0.2)
@@ -49,10 +49,10 @@ 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 (2.4.2)
+    fast_blank (1.0.1)
+    fastimage (2.2.5)
+    ffi (1.15.4)
+    govuk_tech_docs (2.4.3)
       autoprefixer-rails (~> 10.2)
       chronic (~> 0.10.2)
       middleman (~> 4.0)
@@ -129,11 +129,11 @@ GEM
     middleman-syntax (3.2.0)
       middleman-core (>= 3.2)
       rouge (~> 3.2)
-    mini_portile2 (2.5.3)
+    mini_portile2 (2.6.1)
     minitest (5.14.4)
     multi_json (1.15.0)
-    nokogiri (1.11.7)
-      mini_portile2 (~> 2.5.0)
+    nokogiri (1.12.4)
+      mini_portile2 (~> 2.6.1)
       racc (~> 1.4)
     openapi3_parser (0.9.0)
       commonmarker (~> 0.17)
@@ -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)
     parslet (2.0.0)
     psych (3.3.2)
     public_suffix (4.0.6)