src: make model counter in GetCPUInfo() unsigned

This fixes a compiler warning about comparing against
the (unsigned) `NODE_PUSH_VAL_TO_ARRAY_MAX` constant.

PR-URL: #23880
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Eugene Ostroukhov <eostroukhov@google.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Matheus Marchini <mat@mmarchini.me>

src/node_os.cc

@@ -168,7 +168,7 @@ static void GetCPUInfo(const FunctionCallbackInfo<Value>& args) {
   Local<Array> cpus = args[2].As<Array>();
 
   Local<Value> model_argv[NODE_PUSH_VAL_TO_ARRAY_MAX];
-  int model_idx = 0;
+  unsigned int model_idx = 0;
 
   for (i = 0, field_idx = 0; i < count; i++) {
     uv_cpu_info_t* ci = cpu_infos + i;