fix(sdmx_series_ecb_resr): refresh content digest after key strip

sdmx_series_ecb_resr/meta.json

@@ -51,8 +51,8 @@
   "build": {
     "built_at": "2026-06-18T22:34:53.834830Z",
     "parsimony_version": null,
-    "builder": null,
-    "content_sha256": "ce11e107a79bf2762805d5edfff9c0f1c755d258e04c2521ed3cd43a47a7de3d",
+    "builder": "strip-ecb-flow-prefix-keys",
+    "content_sha256": "e68a2e9eb8432a8f01b520a4ea577dfe98975873eb6c6756ba034b70f8cfe160",
     "manifest_contract_sha256": "5f55dcd2e51d97ab48e90e4f8191ae4f6071467360192a93bda43a91c583c5b2"
   }
 }