gh-115114: Add missing slash to file URI prefix file:/ (#115115)

Add missing slash to file URI prefix `file:/`

Author: edgarrmondragon

Doc/whatsnew/3.13.rst

@@ -391,7 +391,7 @@ pathlib
   (Contributed by Barney Gale in :gh:`89812`.)
 
 * Add :meth:`pathlib.Path.from_uri`, a new constructor to create a :class:`pathlib.Path`
-  object from a 'file' URI (``file:/``).
+  object from a 'file' URI (``file://``).
   (Contributed by Barney Gale in :gh:`107465`.)
 
 * Add :meth:`pathlib.PurePath.full_match` for matching paths with