Fix trailing whitespace in extension files

Co-authored-by: lovelydinosaur <647359+lovelydinosaur@users.noreply.github.com>

Author: Copilot

src/mkdocs/extensions/short_codes.py

@@ -26,7 +26,6 @@ def handleMatch(self, m, data):
         el = etree.Element('span')
         el.text = emoji
         return el, m.start(0), m.end(0)
-    
 
 class ShortCodesExtension(markdown.extensions.Extension):
     def extendMarkdown(self, md):

src/mkdocs/extensions/strike_thru.py

@@ -7,7 +7,6 @@ def handleMatch(self, m, data):
         el = etree.Element('del')
         el.text = m.group(1)
         return el, m.start(0), m.end(0)
-    
 
 class StrikeThruExtension(markdown.extensions.Extension):
     def extendMarkdown(self, md):