Redirect hackathon page to new events page

[rly]

Now that nwb.org works, the old hackathon page (https://neurodatawithoutborders.github.io/nwb_hackathons/) is down. It should redirect to https://nwb.org/events.

[rly]

https://neurodatawithoutborders.github.io/nwb_hackathons now redirects to https://nwb.org/nwb_hackathons which is the original page served from the content at https://github.com/NeurodataWithoutBorders/nwb_hackathons/ .

[rly]

I had made https://nwb.org/nwb_hackathons/HCK22_2025_DataConversion_Remote/ redirect to https://nwb.org/events/hck22-2025-dataconversion-remote/ in #77

But after re-deploying the nwb_hackathons repo, now https://nwb.org/nwb_hackathons/HCK22_2025_DataConversion_Remote/ serves the original page. It seems like GitHub Pages handles nwb.org/nwb_hackathons before this Hugo site processes the URL and redirects the user to https://nwb.org/events/hck22-2025-dataconversion-remote/