Update PyCon Poland CFP date (#83)

* Update PyCon Poland CFP date

* extension

---------

Co-authored-by: Jesper Dramsch <[email protected]>

Author: kgawda

_data/conferences.yml

@@ -319,6 +319,7 @@
   link: https://pl.pycon.org/2025/
   cfp_link: https://pyconpl.confreg.pl/events/40-pycon-pl-2025
   cfp: '2025-05-15 23:59:00'
+  cfp_ext: '2025-05-31 23:59:00'
   place: Gliwice, Poland
   start: 2025-08-28
   end: 2025-08-31