LibreNMS: default to an 8 GB disk

With the 4 GB default the release tarball filled the disk; most installs of the last days died writing the version file right after the download.

ct/librenms.sh

@@ -10,7 +10,7 @@ APP="LibreNMS"
 var_tags="${var_tags:-monitoring}"
 var_cpu="${var_cpu:-2}"
 var_ram="${var_ram:-2048}"
-var_disk="${var_disk:-4}"
+var_disk="${var_disk:-8}"
 var_os="${var_os:-debian}"
 var_version="${var_version:-13}"
 var_arm64="${var_arm64:-yes}"