Upgrade Twisted to 26.4.0 (#721)

Author: vstinner

requirements-3.13.txt

@@ -47,7 +47,7 @@ setuptools==82.0.1
 six==1.17.0
 SQLAlchemy==2.0.49
 treq==25.5.0
-Twisted==25.5.0
+Twisted==26.4.0
 txaio==25.12.2
 typing_extensions==4.15.0
 ujson==5.12.1