fix(sdmx_series_ecb_ces): refresh content digest after key strip

sdmx_series_ecb_ces/meta.json

@@ -42,8 +42,8 @@
   "build": {
     "built_at": "2026-06-18T22:29:30.470882Z",
     "parsimony_version": null,
-    "builder": null,
-    "content_sha256": "77fbbd71a209d563ddbe271c1ad988f3250ba67902de82f19f93ae5dc65dee81",
+    "builder": "strip-ecb-flow-prefix-keys",
+    "content_sha256": "8a9364fba4c09c02d737187b5b61ce0ca2ac22868f830a7c91cd9e3786a6e535",
     "manifest_contract_sha256": "7ef70fb7e7beaaefb94ef6fe95954a5fa7cc801d648781d1eecf3785d40b3966"
   }
 }