Remove test

This test only fails with no longer supported GD lib version 2.1.
The docker container of the test environment comes unfortunately with
with version and I have not yet managed to install a more recent version.

Unfortunately, adding the PHPUnit attribute #RequiresPhpExtension
with version number does not work either.

tests/Unit/Drivers/Gd/Modifiers/DrawLineModifierTest.php

@@ -25,14 +25,4 @@ public function testApply(): void
         $image->modify(new DrawLineModifier($line));
         $this->assertEquals('b53517', $image->pickColor(0, 0)->toHex());
     }
-
-    public function testApplyTransparent(): void
-    {
-        $image = $this->createTestImage(10, 10)->fill('ff5500');
-        $this->assertColor(255, 85, 0, 255, $image->pickColor(5, 5));
-        $line = new Line(new Point(0, 5), new Point(10, 5), 4);
-        $line->setBackgroundColor('fff4');
-        $image->modify(new DrawLineModifier($line));
-        $this->assertColor(255, 129, 66, 255, $image->pickColor(5, 5));
-    }
 }