fix command in cherry-picker script (#8738)

.circleci/scripts/cherry-picker.sh

@@ -30,7 +30,7 @@ function get_latest_backport_label {
     fi
 
     latest_backport_label=$(echo "$resp" | jq -r '.[] | select(.name | startswith("backport/")) | .name' | sort -rV | head -n1)
-    echo"$latest_backport_label"
+    echo "$latest_backport_label"
     return 0
 }
 
@@ -181,4 +181,4 @@ done
 if [ "$backport_failures" -ne 0 ]; then
     echo "$backport_failures backports failed"
     exit 1
-fi
+fi