Updated Sebastian's social links

Author: sdaschner

java-champions.yml

@@ -612,6 +612,10 @@ members:
     social:
       twitter: https://twitter.com/DaschnerS
       mastodon: https://mastodon.social/@daschners
+      youtube: https://youtube.com/@SebastianDaschnerIT
+      sessionize: https://sessionize.com/sebastian-daschner
+      github: https://github.com/sdaschner
+      website: https://www.sebastian-daschner.com
     avatar: img/avatars/DaschnerS.png
   - name: Paul J. Deitel
     year: 2005