Skip DBIx::SearchBuilder 1.81 for Oracle

DBIx::SearchBuilder 1.81 introduces a new behavior that empty Contents of
Attachments are saved as empty CLOBs instead of NULL, which breaks the logic
of RT::Attachments::LimitNotEmpty.

etc/cpanfile

@@ -173,6 +173,7 @@ feature 'mariadb' => sub {
 
 feature 'oracle' => sub {
     requires 'DBD::Oracle', '!= 1.23';
+    requires 'DBIx::SearchBuilder', '!= 1.81';
 };
 
 feature 'pg' => sub {