Upgrade seaborn version to 0.12.0

Author: jaeyoo

scripts/ci_validate_tutorials.sh

@@ -20,6 +20,8 @@ pip install jupyter nbclient==0.6.5 jupyter-client==6.1.12 ipython==7.22.0
 pip install ipykernel==5.1.1
 # OpenAI Gym pip package needed for the quantum reinforcement learning tutorial
 pip install gym==0.24.1
+# seaborn has also numpy dependency, it requires version >= 0.12.0.
+pip install seaborn=0.12.0
 # tf_docs pip package needed for noise tutorial.
 pip install -q git+https://github.com/tensorflow/docs
 # Leave the quantum directory, otherwise errors may occur