pt: fix redundant size assert (deepmodeling#3740)

deepmodeling#3738

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## Summary by CodeRabbit

- **Refactor**
- Improved the efficiency of computation by removing unnecessary checks.

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source/lmp/pair_deepmd.cpp

@@ -460,7 +460,6 @@ void PairDeepMD::compute(int eflag, int vflag) {
                "centroid/stress/atom command for 9-element atomic virial.");
   }
   bool do_ghost = true;
-  assert(sizeof(MPI_Comm) == sizeof(int));
   //  dpa2 communication
   commdata_ = (CommBrickDeepMD *)comm;
   double **x = atom->x;