fix typo

Author: AnnePicus

algorithms/differential_equations/time_marching/time_marching.ipynb

@@ -842,7 +842,7 @@
     "execution_preferences = ExecutionPreferences(num_shots=1000000)\n",
     "qmod = create_model(\n",
     "    main,\n",
-    "    preferences=prefereces,\n",
+    "    preferences=preferences,\n",
     "    execution_preferences=execution_preferences,\n",
     "    out_file=\"time_marching\",\n",
     ")\n",
@@ -910,7 +910,7 @@
     "\n",
     "\n",
     "qmod_naive = create_model(\n",
-    "    main, preferences=prefereces, execution_preferences=execution_preferences\n",
+    "    main, preferences=preferences, execution_preferences=execution_preferences\n",
     ")\n",
     "qprog_naive = synthesize(qmod_naive)\n",
     "show(qprog_naive)\n",