Fix url break (#35)

[jm-rivera]

Adds long_month_str to create a full month string. Modifies create_url to add logic dealing with the new url break.
Fixes #35.

[epogrebnyak]

Thanks for submitting a PR, did you test there is any backwards compatibility? Does this mechanism work for earlier dates?

[jm-rivera]

Hi - thanks for getting back to me.

Yes, tested for periods before the last 2 breaks, the previous break etc (2017, 2019, 2020, 2021, 2022, 2023), etc. It seems like when they change the structure, they don't break the permalinks for previous versions.

This PR is only addressing that break, but I think it would be good to update the packages dependencies. Let me know if I can help with that!

[epogrebnyak]

Merging, if you can update the depentencies and notch up our package version in poetry will accept as well.

Welcome to open a separate issue on SDMX endpoint. Does it provide access to all years? Can do some planning in an issue, then integrate your code in weo-reader if you would feel like it.