fix: correct Linux sysfs path for physical core detection (#2186)

src/core/util.cpp

@@ -343,7 +343,7 @@ int32_t sd_get_num_physical_cores() {
     // enumerate the set of thread siblings, num entries is num cores
     std::unordered_set<std::string> siblings;
     for (uint32_t cpu = 0; cpu < UINT32_MAX; ++cpu) {
-        std::ifstream thread_siblings("/sys/devices/system/cpu" + std::to_string(cpu) + "/topology/thread_siblings");
+        std::ifstream thread_siblings("/sys/devices/system/cpu/cpu" + std::to_string(cpu) + "/topology/thread_siblings");
         if (!thread_siblings.is_open()) {
             break;  // no more cpus
         }