Allow single quotes in EXTRACT() for Redshift. (#1795)

Co-authored-by: Roman Borschel <roman@cluvio.com>

tests/sqlparser_redshift.rs

@@ -391,3 +391,9 @@ fn test_parse_nested_quoted_identifier() {
         .parse_sql_statements(r#"SELECT 1 AS ["1]"#)
         .is_err());
 }
+
+#[test]
+fn parse_extract_single_quotes() {
+    let sql = "SELECT EXTRACT('month' FROM my_timestamp) FROM my_table";
+    redshift().verified_stmt(&sql);
+}