[CI] Optimize cherry-pick automation

Author: EmmonsCurse

.github/workflows/cherry-pick.yml

@@ -142,13 +142,16 @@ jobs:
                 NEW_TITLE="[Cherry-Pick] $PR_TITLE($PR_NUMBER)"
               fi
 
-              NEW_BODY="Cherry-pick of #$PR_NUMBER (authored by @${PR_AUTHOR}) to \`$TARGET_BRANCH\`.
+              NEW_BODY=$(cat <<EOF
+Cherry-pick of #$PR_NUMBER (authored by @${PR_AUTHOR}) to \`$TARGET_BRANCH\`.
 
-              devPR:https://github.com/PaddlePaddle/FastDeploy/pull/$PR_NUMBER <!-- For pass CI -->
+devPR:https://github.com/PaddlePaddle/FastDeploy/pull/$PR_NUMBER <!-- For pass CI -->
 
-              ---
+---
 
-              $PR_BODY"
+$PR_BODY
+EOF
+)
 
               # Prepare head ref for PR creation (owner:branch)
               HEAD_REF="${BOT_USERNAME}:${NEW_BRANCH}"