Update Varnish documentation (7.4)

Author: simon04

lib/docs/scrapers/varnish.rb

@@ -9,26 +9,21 @@ class Varnish < UrlScraper
       code: 'https://github.com/varnishcache/varnish-cache'
     }
 
-
     html_filters.push 'varnish/entries', 'sphinx/clean_html'
 
     options[:container] = '.body > section'
-
-
     options[:skip] = %w(genindex.html search.html)
-
     options[:skip_patterns] = [/phk/, /glossary/, /whats-new/]
 
-
     options[:attribution] = <<-HTML
       Copyright &copy; 2006 Verdens Gang AS<br>
       Copyright &copy; 2006&ndash;2020 Varnish Software AS<br>
       Licensed under the BSD-2-Clause License.
     HTML
 
     version do
-      self.release = '7.3.0'
-      self.base_url = 'https://varnish-cache.org/docs/7.3/'
+      self.release = '7.4'
+      self.base_url = "https://varnish-cache.org/docs/#{release}/"
     end
 
     def get_latest_version(opts)