fix(sdmx_series_ecb_safe): refresh content digest after key strip

sdmx_series_ecb_safe/meta.json

@@ -57,8 +57,8 @@
   "build": {
     "built_at": "2026-06-18T22:35:11.599389Z",
     "parsimony_version": null,
-    "builder": null,
-    "content_sha256": "1e05450de5d2c75246e0d6a2e2dd751b7dd0f99eabe3ee8ce9ac4208f93183e0",
+    "builder": "strip-ecb-flow-prefix-keys",
+    "content_sha256": "61a89338ae29d9ec35b98c2171167a806790cebf4692d56b5a52df1f342f64d2",
     "manifest_contract_sha256": "195901256e7e6004c02f3e1d97007538d73fe0e77d89c0c2a48272ebb9f255a0"
   }
 }