Update gitea download and switch to xz files

XZ files are downloaded
Change that any grep is replaced by jq command, and sed for " replace

Add systemd service files as samples

install.sh

@@ -8,14 +8,15 @@ if [ -z "${1}" ]; then
     echo "Please give a Gitea version to upgrade to";
     exit;
 fi;
-if [ ! -f "${download_folder}gitea-${1}-${arch}" ]; then
-    echo "Cannot find file: ${download_folder}gitea-${1}-${arch}";
+file_name="${download_folder}gitea-${1}-${arch}.xz";
+if [ ! -f "${file_name}" ]; then
+    echo "Cannot find file: ${file_name}";
 	exit;
 fi;
 
 echo -e "Update gitea to ${1} ... ";
 systemctl stop gitea;
-cp "${download_folder}gitea-${1}-${arch}" "${target_file}";
+xz -dc "${file_name}" > "${target_file}";
 chmod +x "${target_file}";
 systemctl start gitea;
 echo "[DONE]";