fix(pt): resolve duplicate symbol compilation error in DeepTensorPT createNlistTensor function

Co-authored-by: njzjz <9496702+njzjz@users.noreply.github.com>

Author: Copilot

source/api_cc/src/DeepTensorPT.cc

@@ -14,7 +14,8 @@
 
 using namespace deepmd;
 
-torch::Tensor createNlistTensor(const std::vector<std::vector<int>>& data) {
+static torch::Tensor createNlistTensor(
+    const std::vector<std::vector<int>>& data) {
   size_t total_size = 0;
   for (const auto& row : data) {
     total_size += row.size();