Tedious debug undefined dialectOptions regression fix (#7173)

* Tedious debug undefined dialectOptions fix

* Added PR link to changelog

changelog.md

 # Future
+- [FIXED] MSSQL tedious debug regression fix when dialectOptions are not passed [#7130](https://github.com/sequelize/sequelize/pull/7130)
 - [CHANGED] `setIsolationLevelQuery` to skip under MSSQL dialect, added debug listener for tedious [#7130](https://github.com/sequelize/sequelize/pull/7130)
 - [FIXED] `sourceKey` FOR `hasMany` now also works if a `where` was specified in an `include` [#7141](https://github.com/sequelize/sequelize/issues/7141)
 - [FIXED] `removeColumn` method to support dropping primaryKey column (MSSQL) [#7081](https://github.com/sequelize/sequelize/pull/7081)

lib/dialects/mssql/connection-manager.js

@@ -112,7 +112,7 @@ class ConnectionManager extends AbstractConnectionManager {
         }
       });
       
-      if (config.dialectOptions.debug) {
+      if (config.dialectOptions && config.dialectOptions.debug) {
         connection.on('debug', debugTedious);        
       }