Correct a markup error for an accented character.

Reported by Milan Zamazal <pdm@zamazal.org>.

Doc/lib/libweakref.tex

@@ -5,7 +5,7 @@
 \modulesynopsis{Support for weak references and weak dictionaries.}
 \moduleauthor{Fred L. Drake, Jr.}{fdrake@acm.org}
 \moduleauthor{Neil Schemenauer}{nas@arctrix.com}
-\moduleauthor{Martin von L\o"wis}{martin@loewis.home.cs.tu-berlin.de}
+\moduleauthor{Martin von L\"owis}{martin@loewis.home.cs.tu-berlin.de}
 \sectionauthor{Fred L. Drake, Jr.}{fdrake@acm.org}
 
 \versionadded{2.1}