Add spec for more examples of trailing punctuation that should be ignored

spec/lib/banzai/filter/label_reference_filter_spec.rb

@@ -148,9 +148,11 @@ describe Banzai::Filter::LabelReferenceFilter do
       expect(doc.text).to eq 'See ?g.fm&'
     end
 
-    it 'links with adjacent text' do
-      doc = reference_filter("Label #{reference}.")
-      expect(doc.to_html).to match(%r(<a.+><span.+>\?g\.fm&amp;</span></a>\.))
+    it 'does not include trailing punctuation', :aggregate_failures do
+      ['.', ', ok?', '...', '?', '!', ': is that ok?'].each do |trailing_punctuation|
+        doc = filter("Label #{reference}#{trailing_punctuation}")
+        expect(doc.to_html).to match(%r(<a.+><span.+>\?g\.fm&amp;</span></a>#{Regexp.escape(trailing_punctuation)}))
+      end
     end
 
     it 'ignores invalid label names' do