nextcloud: add missing php7-mod-filter dependency

it's needed when running nextcloud_install:

    + sudo -u nobody php-cli ./occ maintenance:install ...
    An unhandled exception has been thrown:
    Error: Call to undefined function OC\filter_var() in /srv/www/nextcloud/lib/private/Setup.php:479

net/nextcloud/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=nextcloud
 PKG_VERSION:=20.0.4
-PKG_RELEASE:=3
+PKG_RELEASE:=4
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.bz2
 PKG_SOURCE_URL:=https://download.nextcloud.com/server/releases/
@@ -30,7 +30,7 @@ define Package/nextcloud
 	CATEGORY:=Network
 	TITLE:=Nextcloud server
 	URL:=https://nextcloud.com/
-	DEPENDS=+php7-mod-opcache +php7-fpm +php7-cli +sudo +php7-mod-ctype +php7-mod-fileinfo +php7-mod-xmlreader +php7-mod-openssl +php7-mod-hash +php7-mod-gd +php7-mod-xml +php7-mod-xmlwriter +php7-mod-json +php7-mod-mbstring +php7-mod-pcntl +php7-mod-opcache +php7-mod-session +php7-mod-simplexml +php7-mod-iconv +php7-mod-curl +php7-mod-zip +php7-mod-dom +coreutils-stat +php7 +lighttpd-mod-access +php7-mod-intl +icu-full-data
+	DEPENDS=+php7-mod-opcache +php7-fpm +php7-cli +sudo +php7-mod-ctype +php7-mod-fileinfo +php7-mod-xmlreader +php7-mod-openssl +php7-mod-hash +php7-mod-gd +php7-mod-xml +php7-mod-xmlwriter +php7-mod-json +php7-mod-mbstring +php7-mod-pcntl +php7-mod-opcache +php7-mod-session +php7-mod-simplexml +php7-mod-iconv +php7-mod-curl +php7-mod-zip +php7-mod-dom +coreutils-stat +php7 +lighttpd-mod-access +php7-mod-intl +php7-mod-filter +icu-full-data
 endef
 
 define Package/nextcloud-install