[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Author: pre-commit-ci[bot]

tests/roots/test-intersphinx-external-role/demo_module.py

@@ -3,7 +3,7 @@
 
 def probe(x: int) -> int:
     """
-    Summarise.
+    Summarize.
 
     :param x: see :external+demo:doc:`the demo docs <index>`.
     """