Bump minimum govuk_publishing_components version

I've based this new minimum requirement on the oldest versions listed in
the GOV.UK dependency management spreadsheet[1] for projects that're
also using Govspeak. It also needed to be >38.4.1 because of
backwards-incompatible changes we've since made to our tests[2]

[1]: https://docs.google.com/spreadsheets/d/137KZhjctJ8qTKYPnq2QNVkyoIC6ok7KA2G1vErNC6Oo/edit?gid=1160366178#gid=1160366178
[2]: be27793

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Unreleased
 
 * Drop support for Ruby <3.2
+* Drop support for govuk_publishing_components <43.0.0
 
 ## 9.0.0
 

govspeak.gemspec

@@ -31,7 +31,7 @@ library for use in the UK Government Single Domain project'
 
   s.add_dependency "actionview", ">= 6", "< 8.0.2"
   s.add_dependency "addressable", ">= 2.3.8", "< 2.8.8"
-  s.add_dependency "govuk_publishing_components", ">= 35.1"
+  s.add_dependency "govuk_publishing_components", ">= 43"
   s.add_dependency "htmlentities", "~> 4"
   s.add_dependency "i18n", ">= 0.7", "< 1.14.7"
   s.add_dependency "kramdown", ">= 2.3.1", "< 2.5.2"