Add Pandas submodule

[YusufBerki]

Added 2 functions to convert HolidayBase object into Pandas Series or Pandas DataFrame.

These functions were not added to the HolidayBase class as a method in order not to require Pandas in library installation and use. So only those who want to use these functions will have to install Pandas.

Usage:

>>> import holidays
>>> us = holidays.US(years=[2022])

>>> from holidays.pandas import holidays_to_series
>>> holidays_to_series(us)

2022-01-01                                     New Year's Day
2022-01-17                         Martin Luther King Jr. Day
2022-02-21                              Washington's Birthday
2022-05-30                                       Memorial Day
2022-06-19               Juneteenth National Independence Day
2022-06-20    Juneteenth National Independence Day (Observed)
2022-07-04                                   Independence Day
2022-09-05                                          Labor Day
2022-10-10                                       Columbus Day
2022-11-11                                       Veterans Day
2022-11-24                                       Thanksgiving
2022-12-25                                      Christmas Day
2022-12-26                           Christmas Day (Observed)
Name: holiday, dtype: object

[coveralls]

Pull Request Test Coverage Report for Build 2898660991

• 0 of 6 (0.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.06%) to 99.565%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
holidays/pandas.py	0	6	0.0%
<!--	Total:	0	6

Totals
Change from base Build 2897604800:	-0.06%
Covered Lines:	6427
Relevant Lines:	6445

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💛 - Coveralls

[arkid15r]

Hi @YusufBerki,

Thank you for the PR and your work towards improving python-holidays.

I have a couple of thoughts regarding the PR itself and its place in the library:

• first of all I'm not a person who decides the eventual PR acceptance, it's just my own opinion: the code changes are clean and well documented however they don't look very related to the original library purpose.
• it seems that data transformation takes just a couple of extra lines and can be easily done outside of the library.
• and last but not least: it's kind of a requirement to have unit test in order to get your PR accepted, so I suggest adding ones if you still want this code to become a part of the python-holidays.

Thank you!

-- Ark

[dr-prodigy]

Hi @YusufBerki , sorry, I have to agree with @arkid15r : although well documented, your PR doesn't add so much value, but instead enforces a dependency (even if not strict) to Pandas which, not being really required, at the moment we would rather avoid to add. Therefore, we won't receive it as it is: we could reconsider it in case of more valuable additions.

Thanks all the same, cheers