squiggly heredoc doesn't work in ruby < 2.3

Author: manuelmeurer

lib/bootstrap-navbar/helpers/bootstrap4.rb

@@ -90,10 +90,10 @@ def navbar_dropdown_item(text, url = '#', link_options = {}, &block)
  link_options[:class] << 'active' if current_url_or_sub_url?(url)
  link_options[:class] = link_options[:class].join(' ')
  link_attributes = attributes_for_tag(link_options)
- prepare_html <<~HTML.chomp!
- <a href="#{url}"#{link_attributes}>
-  #{text}
- </a>
+ prepare_html <<-HTML.chomp!
+<a href="#{url}"#{link_attributes}>
+ #{text}
+</a>
  HTML
  end