GotoLabelTest: work round removal of assertInternalType()

The `assertInternalType()` method was deprecated in PHPUnit 7.5.0 and removed in PHPUnit 9.0.0.
PHPUnit 7.5.0 introduced dedicated `assertIs*()` (like `assertIsInt()`) methods as a replacement.

As this is only a simple check in these two tests, a PHPUnit feature based toggle seems over the top, so I'm just replacing the assertion with an alternative which will work PHPUnit cross-version.

Author: jrfnl

tests/Core/Tokenizer/GotoLabelTest.php

@@ -32,7 +32,7 @@ public function testGotoStatement($testMarker, $testContent)
 
         $label = $this->getTargetToken($testMarker, T_STRING);
 
-        $this->assertInternalType('int', $label);
+        $this->assertTrue(is_int($label));
         $this->assertSame($testContent, $tokens[$label]['content']);
 
     }//end testGotoStatement()
@@ -78,7 +78,7 @@ public function testGotoDeclaration($testMarker, $testContent)
 
         $label = $this->getTargetToken($testMarker, T_GOTO_LABEL);
 
-        $this->assertInternalType('int', $label);
+        $this->assertTrue(is_int($label));
         $this->assertSame($testContent, $tokens[$label]['content']);
 
     }//end testGotoDeclaration()