nextcloud: Fix external php repo changing the key

images/nextcloud/Dockerfile

 ARG NEXTCLOUD_DATA_PATH
 ARG NEXTCLOUD_BACKUP_PATH
 
-RUN apt-get update && \
+RUN \
+    wget -O /etc/apt/trusted.gpg.d/php.gpg https://packages.sury.org/php/apt.gpg && \
+    apt-get update && \
     apt-get install -y wget bzip2 vim rsync mariadb-client cron sudo php-imagick && \
     apt-get clean
 

images/nextcloud/Dockerfile.template

 ARG NEXTCLOUD_DATA_PATH
 ARG NEXTCLOUD_BACKUP_PATH
 
-RUN apt-get update && \
+RUN \
+    wget -O /etc/apt/trusted.gpg.d/php.gpg https://packages.sury.org/php/apt.gpg && \
+    apt-get update && \
     apt-get install -y wget bzip2 vim rsync mariadb-client cron sudo php-imagick && \
     apt-get clean