Fix parsing of LEFT() and RIGHT() in PostgreSQL

Fixes #108

Author: nene

src/parser.pegjs

@@ -7404,6 +7404,8 @@ postgres_func_keyword
   / LOCALTIME
   / LOCALTIMESTAMP
   / CURRENT_SCHEMA
+  / RIGHT
+  / LEFT
 
 sqlite_func_keyword
   = GLOB

test/expr/func_call.test.ts

@@ -149,7 +149,9 @@ describe("function call", () => {
       it("IF() function", () => {
         testExpr(`IF(x > 3, 'yes', 'no')`);
       });
+    });
 
+    dialect(["mysql", "mariadb", "bigquery", "postgresql"], () => {
       it("LEFT() / RIGHT() functions", () => {
         testExpr(`LEFT('hello', 3)`);
         testExpr(`RIGHT('hello', 3)`);