[base] Expose schema creator as CommonJS (#179)

Author: rexxars

packages/@sanity/base/src/schema/createSchema.js

@@ -2,10 +2,8 @@ import geopoint from './types/geopoint'
 import imageAsset from './types/imageAsset'
 import fileAsset from './types/fileAsset'
 import Schema from '@sanity/schema'
-export default schemaDef => {
-  return Schema.compile({
-    name: schemaDef.name,
-    types: [...schemaDef.types, geopoint, imageAsset, fileAsset]
-  })
-}
 
+module.exports = schemaDef => Schema.compile({
+  name: schemaDef.name,
+  types: [...schemaDef.types, geopoint, imageAsset, fileAsset]
+})