Update Matplotlib documentation (3.4.3)

Fixes #1650.

assets/stylesheets/pages/_sphinx.scss

@@ -39,6 +39,8 @@
   .admonition-title + dl { padding-top: .5em; }
 
   td > div { margin: 0 !important; }
+
+  .classifier:before { content:": " }
 }
 
 ._sphinx {

lib/docs/filters/sphinx/clean_html.rb

@@ -58,6 +58,7 @@ module Docs
         end
 
         css('dt').each do |node|
+          next if current_url.host == 'matplotlib.org'
           next unless node['id'] || node.at_css('code, .classifier')
           links = []
           links << node.children.last.remove while node.children.last.try(:name) == 'a'

lib/docs/scrapers/matplotlib.rb

@@ -21,7 +21,7 @@ module Docs
     HTML
 
     version '3.4' do
-      self.release = '3.4.1'
+      self.release = '3.4.3'
       self.base_urls = [
         "https://matplotlib.org/#{release}/api/",
         "https://matplotlib.org/#{release}/mpl_toolkits/mplot3d/",