Update path to codespace tutorial database

In https://github.com/github/codespaces-codeql/pull/12 we moved
the source for our tutorial database into `.tours` in order to
avoid confusing the user when we load the database into the
workspace, since they'd see two databases.

Since this is just the source, we'd like to hide it.

extensions/ql-vscode/src/local-databases-ui.ts

@@ -375,7 +375,7 @@ export class DatabaseUI extends DisposableObject {
         // This specifically refers to the database folder in
         // https://github.com/github/codespaces-codeql
         const uri = Uri.parse(
-          `${workspace.workspaceFolders[0].uri}/codeql-tutorial-database`,
+          `${workspace.workspaceFolders[0].uri}/.tours/codeql-tutorial-database`,
         );
 
         let databaseItem = this.databaseManager.findDatabaseItem(uri);