Use strip to remove leading/trailing spaces

Change based on comments in MR #27025

lib/banzai/filter/table_of_contents_filter.rb

@@ -18,7 +18,6 @@ module Banzai
     #          `li` child elements.
     class TableOfContentsFilter < HTML::Pipeline::Filter
       PUNCTUATION_REGEXP = /[^\p{Word}\- ]/u.freeze
-      LEADING_OR_TRAILING_SPACE_REGEXP = /^\p{Space}+|\p{Space}+$/.freeze
 
       def call
         return doc if context[:no_header_anchors]
@@ -32,7 +31,7 @@ module Banzai
           if header_content = node.children.first
             id = node
               .text
-              .gsub(LEADING_OR_TRAILING_SPACE_REGEXP, '') # remove leading and trailing spaces
+              .strip
               .downcase
               .gsub(PUNCTUATION_REGEXP, '') # remove punctuation
               .tr(' ', '-') # replace spaces with dash

spec/lib/banzai/filter/table_of_contents_filter_spec.rb

@@ -59,7 +59,7 @@ describe Banzai::Filter::TableOfContentsFilter do
       end
 
       it 'removes any leading or trailing spaces' do
-        doc = filter(header(1, " \r\n \t Title with spaces \r\n\t "))
+        doc = filter(header(1, " \r\n\tTitle with spaces\r\n\t "))
         expect(doc.css('h1 a').first.attr('href')).to eq '#title-with-spaces'
       end