fix: fix remove_language_code not removing language codes from region-specific url paths

This helper function wasn't capable of removing region-specific language codes from any url 'cause the regex only checked for two-letter language codes (like 'en'), ignoring region-specific locales like 'es-ar'

wger/utils/helpers.py

@@ -200,5 +200,5 @@ def remove_language_code(path):
     Removes optional language code at the start of a path
     """
 
-    pattern = r'^/[a-z]{2}(?=/)'
-    return re.sub(pattern, '', path)
+    pattern = r'^/[a-z]{2}(-[a-z]{2,4})?/'
+    return re.sub(pattern, '/', path)