src: initialize worker's stack_base_ field

Coverity was complaining that this field was not initialized.

PR-URL: #26739
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

src/node_worker.h

@@ -70,7 +70,7 @@ class Worker : public AsyncWrap {
   bool thread_joined_ = true;
   int exit_code_ = 0;
   uint64_t thread_id_ = -1;
-  uintptr_t stack_base_;
+  uintptr_t stack_base_ = 0;
 
   // Full size of the thread's stack.
   static constexpr size_t kStackSize = 4 * 1024 * 1024;