Add bluesky to social media links (#214)

Author: MangoIV

content/zurihac2025/index.html

@@ -161,6 +161,7 @@ <h2 id="contact">Contact</h2>
     <a href="mailto:[email protected],[email protected]">to the organizers</a>.
     You can also interact with us on our social media accounts:
     <a href="https://fosstodon.org/@zurihac">Mastodon</a>,
+    <a href="https://bsky.app/profile/zurihac.bsky.social">Bluesky</a>,
     <a href="https://twitter.com/zurihac">Twitter</a>.
   </p>
   <h2>Legal</h2>