Fix PHPunit test framework class extensions

Author: greenlion

tests/cases/parser/issue320Test.php

@@ -41,7 +41,7 @@
 use PHPSQLParser\PHPSQLParser;
 use PHPSQLParser\PHPSQLCreator;
 
-class issue320Test extends \PHPUnit_Framework_TestCase
+class issue320Test extends \PHPUnit\Framework\TestCase
 {
     public function test_no_warning_is_issued_when_help_table_is_used()
     {

tests/cases/parser/issue335Test.php

@@ -39,7 +39,7 @@
 
 use PHPSQLParser\PHPSQLParser;
 
-class issue335Test extends \PHPUnit_Framework_TestCase
+class issue335Test extends \PHPUnit\Framework\TestCase
 {
     /**
      * @test

tests/cases/parser/issue338Test.php

@@ -4,7 +4,7 @@
 
 use PHPSQLParser\PHPSQLParser;
 
-class issue338Test extends \PHPUnit_Framework_TestCase
+class issue338Test extends \PHPUnit\Framework\TestCase
 {
 	public function testIssue338() {
 		$sql = "SELECT id, date, type as type, libelle as libelle, TRUNCATE(debit, 2) as debit, ROUND(COALESCE(credit, 0) - COALESCE(debit, 0), 2) as solde FROM compte_cp";