Fix apk ERROR: UNTRUSTED signature

fetch http://nl.alpinelinux.org/alpine/latest-stable/community/x86_64/APKINDEX.tar.gz
    ERROR: http://nl.alpinelinux.org/alpine/latest-stable/community: UNTRUSTED signature
    WARNING: Ignoring http://nl.alpinelinux.org/alpine/latest-stable/community: No such file or directory

Dockerfile

@@ -35,7 +35,7 @@ ARG HOME=/opt/pleroma
 ARG DATA=/var/lib/pleroma
 
 RUN echo "http://nl.alpinelinux.org/alpine/latest-stable/community" >> /etc/apk/repositories &&\
-	apk update &&\
+	apk update --allow-untrusted &&\
 	apk add exiftool ffmpeg imagemagick libmagic ncurses postgresql-client &&\
 	adduser --system --shell /bin/false -u $UID -g $GID --home ${HOME} pleroma &&\
 	mkdir -p ${DATA}/uploads &&\