Fix renovate image selector output for docker run

.gitea/workflows/renovate.yml

@@ -62,20 +62,20 @@ jobs:
 
           pick_renovate_image() {
             for candidate in "${RENOVATE_IMAGE_PRIMARY}" "${RENOVATE_IMAGE_FALLBACK}"; do
-              echo "Trying Renovate image candidate: ${candidate}"
+              echo "Trying Renovate image candidate: ${candidate}" >&2
 
               if docker image inspect "${candidate}" >/dev/null 2>&1; then
-                echo "Using cached Renovate image: ${candidate}"
+                echo "Using cached Renovate image: ${candidate}" >&2
-                echo "${candidate}"
+                printf '%s\n' "${candidate}"
                 return 0
               fi
 
               if retry_cmd 3 15 docker pull "${candidate}"; then
-                echo "${candidate}"
+                printf '%s\n' "${candidate}"
                 return 0
               fi
 
-              echo "⚠ Renovate image candidate failed: ${candidate}"
+              echo "⚠ Renovate image candidate failed: ${candidate}" >&2
             done
 
             return 1