fix: remove abort event listener on successful completion in fetchWithTimeout

When an AbortSignal is passed to fetchWithTimeout, the method adds an
event listener to forward abort events to the internal controller but
never removes it on successful completion. In Deno, this refs the
underlying timer of AbortSignal.timeout(), preventing the process from
exiting until the full timeout duration elapses.

Fixes #1811

Author: jordanjennings

src/client.ts

@@ -892,6 +892,7 @@ export class OpenAI {
       return await this.fetch.call(undefined, url, fetchOptions);
     } finally {
       clearTimeout(timeout);
+      if (signal) signal.removeEventListener('abort', abort);
     }
   }