Pandas version pinned to <2

[valentina-s]

Currently, testing does not work with pandas >=2, so it is pinned to 1.5.3.

[Galaxy3696]

Some tests failed in the pandas >=2 because they removed argument datetime_is_numeric from DataFrame.describe() and Series.describe()as datetime data will always be summarized as numeric data. (GH 34798).
I have implemented a fix for this issue: commit

[leewujung]

@Galaxy3696 : Would you like to submit a PR for your fix? Would be great to unpin pandas!

[leewujung]

This is resolved via #183 .