Update install.sh

install.sh

@@ -62,7 +62,7 @@ if [[ x"${release}" == x"centos" ]]; then
         echo -e "${red} Please use CentOS 8 or higher ${plain}\n" && exit 1
     fi
 elif [[ x"${release}" == x"ubuntu" ]]; then
-    if [[ ${os_version} -lt 18 ]]; then
+    if [[ ${os_version} -lt 20 ]]; then
         echo -e "${red} Please use Ubuntu 20 or higher ${plain}\n" && exit 1
     fi
 elif [[ x"${release}" == x"debian" ]]; then