FIX finding github anchor (#172)

Github changed their css class.

CHANGELOG.md

@@ -1,7 +1,7 @@
 # master (unreleased)
 
 Changed:
-* know rely on rubygems metadata to get the changelog uri.
+* rely on rubygems metadata to get the changelog uri.
   It means that for any gem not hosted on rubygems, the changelog won’t be found.
 
 Deprecated:

lib/gem_updater/changelog_parser/github_parser.rb

@@ -37,7 +37,7 @@ def document
       # @param doc [Nokogiri::HTML4::Document] document
       # @return [String, nil] anchor's href
       def find_anchor(doc)
-        anchor = doc.xpath('//a[contains(@class, "anchor")]').find do |element|
+        anchor = doc.xpath('//a[contains(@class, "heading-link")]').find do |element|
           element.attr('href').match(version.delete('.'))
         end
         return unless anchor

spec/acceptance/gem_update_spec.rb

@@ -19,8 +19,8 @@
       * regexp_parser 2.6.1 → 2.8.1
       [changelog](https://github.com/ammar/regexp_parser/blob/master/CHANGELOG.md#281---2023-06-10---janosch-müller)
 
-      * rubocop 1.38.0 → 1.56.3
-      [changelog](https://github.com/rubocop/rubocop/blob/master/CHANGELOG.md#1563-2023-09-11)
+      * rubocop 1.38.0 → 1.56.4
+      [changelog](https://github.com/rubocop/rubocop/blob/master/CHANGELOG.md)
 
     OUTPUT
   end