Fix ISR issue with index.ts

For the root path `/` the `s3StorePage` was not correctly storing to the index.html file and instead was storing as `.html`

Added an extra regex replace() to deal with the root path.

Author: J3tto

packages/libs/lambda-at-edge/src/s3/s3StorePage.ts

@@ -30,6 +30,7 @@ export const s3StorePage = async (
     ? `${options.basePath.replace(/^\//, "")}/`
     : "";
   const baseKey = options.uri
+    .replace(/^\/$/, "index")
     .replace(/^\//, "")
     .replace(/\.(json|html)$/, "")
     .replace(/^_next\/data\/[^\/]*\//, "");