[heavy_data] Retrieve data from yahoo finance

[Jiarui-ZH]

To bypass the error encountered when retrieving data directly from y-finance, a script was written that, when run, retrieves the relevant data from y-finance and stores it in a CSV file.

[kp992]

Thanks @Jiarui-ZH . Please update this branch on top of wasm which will remove this conflicts. Also, please move the data sets to https://github.com/QuantEcon/data. We will use url to fetch data from the repository https://raw.github...

[kp992]

I would recommend to create new PR because the datasets are already added in the commit history and we don't want to populate them in this repository. You can use the following steps:

1. Close the PR.
2. Move the datasets to QuantEcon/data repository under https://github.com/QuantEcon/data/tree/main/lecture-python-intro/dynamic.
3. Add the script that you use to get this data in https://github.com/QuantEcon/data/tree/main/lecture-python-intro/scripts.
4. Open the local repository of lecture-python-intro and use the following commands to create a branch.

$ git remote add lpi https://github.com/QuantEcon/lecture-python-intro.git
$ git fetch lpi
$ git checkout lpi/wasm
$ git checkout -b my_new_branch_name

Start adding your commits in my_new_branch_name and raise a PR.

You can use the last 3 commands every time you want to create a new branch and raise PR against wasm branch. The first command is just used once.