fix(sdmx_series_ecb_spf): refresh content digest after key strip

sdmx_series_ecb_spf/meta.json

@@ -42,8 +42,8 @@
   "build": {
     "built_at": "2026-06-18T22:35:15.034042Z",
     "parsimony_version": null,
-    "builder": null,
-    "content_sha256": "e7238b2279f9fe1346ed9259392a5afaa42b15cbc297bc20f0518a7cd9fa9ace",
+    "builder": "strip-ecb-flow-prefix-keys",
+    "content_sha256": "388e42cff269ea2882d093dd3bf86f902b1c5c8543110a04a8b501e5a713530c",
     "manifest_contract_sha256": "02124eafa0206fd5f622f093d212fea0d8538c2f1ca25f2aef0daf396b04a78e"
   }
 }