Update links for Ivar

Author: ivargrimstad

java-champions.yml

@@ -1094,7 +1094,13 @@ members:
     city: Malmo
     social:
       twitter: https://twitter.com/ivar_grimstad
+      mastodon: https://mastodon.social/deck/@ivar_grimstad
       bluesky: https://bsky.app/profile/ivargrimstad.bsky.social
+      linkedin: https://www.linkedin.com/in/ivargrimstad/
+      github: https://github.com/ivargrimstad
+      website: https://www.agilejava.eu/
+      sessionize: https://sessionize.com/ivar-grimstad/
+      speakerdeck: https://speakerdeck.com/ivargrimstad
     avatar: img/avatars/ivar_grimstad.png
   - name: Sanne Grinovero
     year: 2020