common: set repeat = false for simulation_cell

meta_info/nomad_meta_info/common.nomadmetainfo.json

@@ -2594,7 +2594,7 @@
       "description": "Simulation cell (lattice vectors). The first index is x,y,z and the second index the lattice vector.",
       "dtypeStr": "f",
       "name": "simulation_cell",
-      "repeats": true,
+      "repeats": false,
       "shape": [
         3,
         3