ui: Change wording of string
I am a member of the German translation team. While proofreading my translation proposal, @ckirbach found a "German version" (not really a 1:1 translation) of this string, that inspired me to this Merge Request.
What do you think? You may want to look into this before Feb 27, which is the date of String Freeze for GNOME 40.
Please do not hesitate to give (harsh) feedback, this is my first contribution to a GNOME module. Also, I couldn't find any contributing guidelines, so my commit message might not fit in your scheme.
Happy to do another MR with an updated message, if this is an issue!