Add DuckDB functions

Author: nene

src/languages/duckdb/duckdb.formatter.ts

@@ -1,6 +1,6 @@
 import { DialectOptions } from '../../dialect.js';
 import { expandPhrases } from '../../expandPhrases.js';
-import { functions } from '../postgresql/postgresql.functions.js';
+import { functions } from './duckdb.functions.js';
 import { dataTypes, keywords } from './duckdb.keywords.js';
 
 const reservedSelect = expandPhrases(['SELECT [ALL | DISTINCT]']);