Use os-release for host info

resolves github/ghes#7336

Author: djdefi

bin/ghe-backup

@@ -231,9 +231,11 @@ fi
 
 # Output system information of the backup host
 
-# If /etc/issue.net exists, use it to get the OS version
-if [ -f /etc/issue.net ]; then
-  echo "Running on: $(cat /etc/issue.net)"
+# If /etc/os-release exists, use it to get the OS version
+if [ -f /etc/os-release ]; then
+  OS_NAME=$(grep '^NAME' /etc/os-release | cut -d'"' -f2)
+  VERSION_ID=$(grep '^VERSION_ID' /etc/os-release | cut -d'"' -f2)
+  echo "Running on: $OS_NAME $VERSION_ID"
 else
   echo "Running on: Unknown OS"
 fi