remove sx import in RB notebook

Author: nathan-classiq

applications/benchmarking/randomized_benchmarking/randomized_benchmarking.ipynb

@@ -32,7 +32,6 @@
     "from functools import partial\n",
     "\n",
     "from classiq import *\n",
-    "from classiq.qmod.builtins.functions.standard_gates import SX\n",
     "from classiq.qmod.symbolic import pi\n",
     "\n",
     "# a) Parameter definitions\n",