strip leftover sdmx key from catalog meta.json

meta.json

@@ -25,6 +25,5 @@
     "builder": "packages/bdf/scripts/build_catalog.py",
     "content_sha256": "80d6d49ed4af93c653defada2b9ce9bea089325246ce46c7745bed195826c3a1",
     "manifest_contract_sha256": "b3a04cbc60777e1b903cf4e4881572c17f139771140a7e0bcd217810bb4bec16"
-  },
-  "sdmx": null
-}
+  }
+}