Fixed string in German translation that causes segfault.

Applied patch by Christoph Berg <cb@df7cb.de> to replace placeholder "%s" by
correct string.

src/backend/po/de.po

@@ -14712,7 +14712,7 @@ msgid ""
 "If your source string is not fixed-width, try using the \"FM\" modifier."
 msgstr ""
 "Wenn die Quellzeichenkette keine feste Breite hat, versuchen Sie den "
-"Modifikator »%s«."
+"Modifikator »FM«."
 #: utils/adt/formatting.c:2113 utils/adt/formatting.c:2126
 #: utils/adt/formatting.c:2256