fix: account for public grantee

Author: soedirgo

Diff for: ansible/files/admin_api_scripts/pg_upgrade_scripts/common.sh

@@ -356,6 +356,7 @@ begin
                        end
                      , case when rec.grantee = 'postgres'::regrole then 'supabase_admin'
                             when rec.grantee = 'supabase_admin'::regrole then 'postgres'
+                            when rec.grantee = 0 then 'public'
                             else rec.grantee::regrole
                        end
                      ));
@@ -382,7 +383,7 @@ begin
                             when obj->>'objtype' = 'T' then 'types'
                             when obj->>'objtype' = 'n' then 'schemas'
                        end
-                     , rec.grantee::regrole
+                     , case when rec.grantee = 0 then 'public' else rec.grantee::regrole end
                      , case when rec.is_grantable then 'with grant option' else '' end
                      ));
       end if;