Pontoon: Update German (de) localization of Firefox Monitor Website

Co-authored-by: Michael Köhler <michael.koehler1@gmx.de>

locales/de/app.ftl

@@ -11,7 +11,7 @@
 -brand-pocket = Pocket
 -brand-lockwise = Firefox Lockwise
 -brand-send = Firefox Send
--brand-fpn = Firefox-Datenschutznetzwerk
+-brand-fpn = Firefox Private Network
 
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