[github] Upgrade Fluss version 0.8.0 in BUG issue template

Author: wuchong

.github/ISSUE_TEMPLATE/bug.yml

@@ -39,9 +39,8 @@ body:
       description: What Fluss version are you using?
       multiple: false
       options:
-        - "0.7.0 (latest release)"
-        - "0.6.0"
-        - "0.5.0"
+        - "0.8.0 (latest release)"
+        - "0.7.0"
         - "main (development)"
     validations:
       required: true