Support cloudflare worker in conditional exports

cloudflare/workers-sdk#84
cloudflare/workers-sdk#93

Author: xenova

package.json

@@ -16,6 +16,10 @@
         "default": "./dist/transformers.node.cjs"
       }
     },
+    "worker": {
+      "types": "./types/transformers.d.ts",
+      "default": "./dist/transformers.js"
+    },
     "default": {
       "types": "./types/transformers.d.ts",
       "default": "./dist/transformers.web.js"