fix(sdmx_series_ecb_sst): refresh content digest after key strip

sdmx_series_ecb_sst/meta.json

@@ -42,8 +42,8 @@
   "build": {
     "built_at": "2026-06-18T22:35:18.455088Z",
     "parsimony_version": null,
-    "builder": null,
-    "content_sha256": "0ccfc174b0c895f4d4268314338a1dbd704cd5ddfe9265eb4e4c399eb7e6baca",
+    "builder": "strip-ecb-flow-prefix-keys",
+    "content_sha256": "c06097a6836aa7b0e68764f2310640693b61c58ef099284e7f2317cbc1184af1",
     "manifest_contract_sha256": "f04d0b064a28c48b173f0eafb2d87e349d6c2e9554b50b6e4b01b326026107bc"
   }
 }