Refuse to run the PBS 4 upgrade on a Proxmox VE host

Nothing checked that the host is a Backup Server. On a PVE host the
first step stopped only because tar found no /etc/proxmox-backup (exit
2); answering "no" to that backup would have gone on to delete
/etc/apt/sources.list.d/*.list, add the PBS repositories and
dist-upgrade. Stop with the same message post-pbs-install uses.

ct/technitiumdns.sh

@@ -47,7 +47,7 @@ function update_script() {
     $STD apt install -y aspnetcore-runtime-10.0
   fi
 
-  RELEASE=$(get_latest_github_release "TechnitiumSoftware/DnsServer")
+  RELEASE=$(curl -fsSL https://technitium.com/dns/ | grep -oP 'Version \K[\d.]+')
   if [[ ! -f ~/.technitium || ${RELEASE} != "$(cat ~/.technitium 2>/dev/null)" ]]; then
     fetch_and_deploy_from_url "https://download.technitium.com/dns/DnsServerPortable.tar.gz" /opt/technitium/dns
     echo "${RELEASE}" >~/.technitium

install/technitiumdns-install.sh

@@ -23,7 +23,7 @@ setup_deb822_repo \
 $STD apt install -y aspnetcore-runtime-10.0
 msg_ok "Installed Dependencies"
 
-RELEASE=$(get_latest_github_release "TechnitiumSoftware/DnsServer")
+RELEASE=$(curl -fsSL https://technitium.com/dns/ | grep -oP 'Version \K[\d.]+')
 fetch_and_deploy_from_url "https://download.technitium.com/dns/DnsServerPortable.tar.gz" /opt/technitium/dns
 echo "${RELEASE}" >~/.technitium
 

tools/pve/pbs4-upgrade.sh

@@ -199,6 +199,11 @@ while true; do
   esac
 done
 
+if command -v pveversion >/dev/null 2>&1; then
+  echo -e "\n🛑  PVE Detected, Wrong Script!\n"
+  exit 232
+fi
+
 if [ "$(dpkg --print-architecture 2>/dev/null)" = "arm64" ]; then
   header_info
   msg_error "This upgrade script targets the amd64 Proxmox repositories and is not supported on ARM64."