Update bug issue template (#496)

Author: ndrluis

.github/ISSUE_TEMPLATE/iceberg_bug_report.yml

@@ -9,7 +9,8 @@ body:
       description: What Apache Iceberg version are you using?
       multiple: false
       options:
-        - "0.5.0 (latest release)"
+        - "0.6.0 (latest release)"
+        - "0.5.0"
         - "0.4.0"
         - "0.3.0"
         - "0.2.0"