Make cloudflare package export (#2061)

Cloudflare's runtime uses the "workerd" condition export key as described [here](https://developers.cloudflare.com/workers/wrangler/bundling/#conditional-exports) and [here](https://runtime-keys.proposal.wintercg.org/#workerd).

Co-authored-by: anniel-stripe <97691964+anniel-stripe@users.noreply.github.com>

package.json

@@ -88,6 +88,10 @@
       "import": "./esm/stripe.esm.worker.js",
       "require": "./cjs/stripe.cjs.worker.js"
     },
+    "workerd": {
+      "import": "./esm/stripe.esm.worker.js",
+      "require": "./cjs/stripe.cjs.worker.js"
+    },
     "default": {
       "import": "./esm/stripe.esm.node.js",
       "require": "./cjs/stripe.cjs.node.js"