strip leftover sdmx key from catalog meta.json

meta.json

@@ -25,6 +25,5 @@
     "builder": "packages/eia/scripts/build_catalog.py",
     "content_sha256": "eb3c5bb7091af35a2cca51a86c389d7ef6fa3ef24eec2f692ede31a6b6f4b134",
     "manifest_contract_sha256": "77c5b8428fc4bb847a2879983e2eaac7227a710b6d3a729dccfc163dd317f67c"
-  },
-  "sdmx": null
-}
+  }
+}