Update isolate_manager dependency version

[brandon-bethke-timu]

Fixes this issue on Flutter 3.41.7

Target dart2js failed: ProcessException: Process exited abnormally with exit code 1:
../../../.pub-cache/hosted/pub.dev/isolate_contactor-4.2.0/lib/src/isolate_contactor/web_platform/isolate_contactor_web_worker.dart:120:31:
Error: The argument type 'String' can't be assigned to the parameter type 'JSAny'.
      Worker("$_workerName.js"),