fix: ci workers builds failure by fixing extension and configurations

* Renames `workers/index.js` to `workers/index.mjs` to match the entry point ESM requirement.
* Modifies `wrangler.toml` to configure `workers/index.mjs` and compatibility date.

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

Author: igor-holt

workers/index.js workers/index.mjsworkers/index.js renamed to workers/index.mjs

@@ -1,6 +1,6 @@
 name            = "yennefer"
-main            = "workers/index.js"
-compatibility_date  = "2024-09-23"
+main            = "workers/index.mjs"
+compatibility_date  = "2024-04-01"
 compatibility_flags = ["nodejs_compat"]
 
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