Memory Leak in InputMeshTri

Memory for lines is created but never destroyed:
https://github.com/CFDEMproject/LIGGGHTS-PUBLIC/blob/3.3.1/src/input_mes...

Add memory->destroy(lines); at the end of the function to fix the leak.
https://github.com/CFDEMproject/LIGGGHTS-PUBLIC/blob/3.3.1/src/input_mes...