Fix sed gobbling for a newline replacement

Current version of `sed` on `ubuntu:jammy-20221101` stopped working as before.
As a result newlines weren't showing properly in PR body.
Output was polluted by `^NowALiNiA^` strings, which should be newlines.

Author: ChristophShyper

entrypoint.sh

@@ -129,7 +129,7 @@ if [[ "${INPUT_GET_DIFF}" ==  "true" ]]; then
   TEMPLATE=$(echo -e "${TEMPLATE}" | sed ':a;N;$!ba; s#<!-- Diff files -->#<!-- Diff files - START -->\n'"${GIT_DIFF}"'\n<!-- Diff files - END -->#g')
   TEMPLATE=$(echo -e "${TEMPLATE}" | sed ':a;N;$!ba; s#<!-- Diff files - START -->.*<!-- Diff files - END -->#<!-- Diff files - START -->\n'"${GIT_DIFF}"'\n<!-- Diff files - END -->#g')
 fi
-TEMPLATE=$(echo -e "${TEMPLATE}" | sed 's|\^HaSz\^|#|g' | sed ':a;N;$!ba; s|\^NowALiNiA\^|\n|g')
+TEMPLATE=$(echo -e "${TEMPLATE}" | sed 's|\^HaSz\^|#|g' | sed '1h;2,$H;$!d;g; s|\^NowALiNiA\^|\n|g')
 
 if [[ -z "${PR_NUMBER}" ]]; then
   echo -e "\nSetting all arguments..."