[DBManager] Fix exception raised when adding a new Spatialite connection

This was accidentaly broken since 1f0fce7

Fixes #15274

python/plugins/db_manager/db_plugins/spatialite/plugin.py

@@ -99,7 +99,7 @@ def addConnectionActionSlot(self, item, action, parent, index):
         uri = QgsDataSourceURI()
         uri.setDatabase(filename)
         self.addConnection(conn_name, uri)
-        index.internalPointer().itemChanged.emit()
+        index.internalPointer().itemChanged()
 
 
 class SLDatabase(Database):