strip leftover sdmx key from catalog meta.json

meta.json

@@ -25,6 +25,5 @@
     "builder": "packages/bde/scripts/build_catalog.py",
     "content_sha256": "b50388a1387d89d30a48d18e036a21cdfa6ca346695b492e3638b0422cd9a650",
     "manifest_contract_sha256": "c989a306f95907e2fdba2916b6315b0f6f55b8f0b34facec196a92ff0819cc8a"
-  },
-  "sdmx": null
-}
+  }
+}