chore: format matrix as square

Author: VsevolodX

other/materials_designer/create_supercell.ipynb

@@ -34,7 +34,11 @@
    "cell_type": "code",
    "outputs": [],
    "source": [
-    "SUPERCELL_MATRIX = [[3, 0, 0], [0, 3, 0], [0, 0, 1]] \n",
+    "SUPERCELL_MATRIX = [\n",
+    "    [3, 0, 0], \n",
+    "    [0, 3, 0], \n",
+    "    [0, 0, 1]\n",
+    "] \n",
     "\n",
     "# or use the scaling factor\n",
     "SCALING_FACTOR = None # [3, 3, 1]"