Fix news entry grammar

Author: aisk

Misc/NEWS.d/next/Core_and_Builtins/2026-06-21-23-23-24.gh-issue-151847.5uNKTL.rst

@@ -1,3 +1,3 @@
 When formatting a ``str`` or ``bytes`` with ``%``, passing ``-sys.maxsize -
-1`` as the width previously negated it, this is undefined behaviour in C. it
+1`` as the width previously negated it, this is undefined behaviour in C. It
 now raises :exc:`OverflowError`.