Bump NextCloudPi to Debian 13, matching upstream's trixie move

Upstream's master ncp.cfg now targets release "trixie" (Debian 13);
bookworm (Debian 12) is no longer in the supported check_distro list
at all. Move our own default to Debian 13 and pin the installer ref
to v1.58.0-rc1, the only tagged ref with release=trixie so far (no
stable trixie release exists yet upstream).

ct/nextcloudpi.sh

@@ -11,7 +11,7 @@ var_cpu="${var_cpu:-2}"
 var_ram="${var_ram:-2048}"
 var_disk="${var_disk:-8}"
 var_os="${var_os:-debian}"
-var_version="${var_version:-12}"
+var_version="${var_version:-13}"
 var_arm64="${var_arm64:-yes}"
 var_unprivileged="${var_unprivileged:-1}"
 

install/nextcloudpi-install.sh

@@ -13,7 +13,7 @@ setting_up_container
 network_check
 update_os
 
-NCP_INSTALLER_REF="v1.57.1"
+NCP_INSTALLER_REF="v1.58.0-rc1"
 
 msg_warn "WARNING: This script will run an external installer from a third-party source (https://nextcloudpi.com/)."
 msg_warn "The following code is NOT maintained or audited by our repository."