Update copyright year to the current year

[Vadim-Khristenko]

The copyright year mentioned in the repository needs to be updated to reflect the current year.

https://github.com/MasterGroosha/aiogram-3-guide/blob/6cb3283981b1f4d18a52de9cb7f3c954cf60e3d7/mkdocs.yml#L15

[MasterGroosha]

That’s an interesting one. On the one hand, that’s normal to automatically update copyright year on build: https://github.com/squidfunk/mkdocs-material/discussions/4969

On the other hand, I believe that copyright years should reflect time period, when website was actively updated. For example, if there were no meaningful changes this year, copyright should not be updated.