Fix the esm paths of the exports.

I updated the build files but somehow forgot to update the `exports`. I think I didn't catch it in my testing because the `types` were still correct.

Thanks to @arcanis for diagnosing.
Hopefully fixes #53.

Author: lgarron

package.json

@@ -11,11 +11,11 @@
   "bin": "dist/bin/main.js",
   "exports": {
     ".": {
-      "import": "./dist/webauthn-json.js",
+      "import": "./dist/esm/webauthn-json.js",
       "types": "./dist/types/index.d.ts"
     },
     "./extended": {
-      "import": "./dist/webauthn-json.extended.js",
+      "import": "./dist/esm/webauthn-json.extended.js",
       "types": "./dist/types/extended.d.ts"
     }
   },