Add Gdańsk (PL) Open Data portal

[applowiec]

This PR adds the official Open Data portal of the City of Gdańsk (Poland).

• Name: Gdańsk Open Data
• Description: Official open data portal of the City of Gdańsk (Poland).
• URL: https://otwartedane.gdansk.pl/
• Category: Government
• Type: city
• Country: PL
• City: Gdańsk

This complements the previous contribution of Warsaw Open Data, continuing the inclusion of Polish municipal open data portals into the APD Core project.

[applowiec]

Hi, following up on my previous contribution (Warsaw Open Data), I’m adding the official Gdańsk Open Data portal.
Looking forward to your feedback and happy to continue expanding the Polish open data section 🚀

[ppival]

Thanks, @applowiec would you correct the field labels as in this example? (title and homepage instead of Name and URL)

title: New Dataset Name
homepage: https://example.com
category: Government

I tried to edit your submission manually, but it didn't go through for some reason.