Add test coverage for drawCell with null align parameter (#41)

* Add test case for drawCell with null align parameter

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: andersonls <1561038+andersonls@users.noreply.github.com>

Author: Copilot

tests/ZplTest.php

@@ -110,6 +110,14 @@ public function drawCell(): void
         $this->assertEquals("^XA\n^FO0,0^GB100,10,3,B,0^FS\n^FO10,2.5\n^FB90,7.5,0,C\n^FH^FDHello World^FS\n^XZ\n", $this->getZpl());
     }
 
+    #[Test]
+    public function drawCellWithNullAlign(): void
+    {
+        $this->driver->drawCell(100, 10, 'Hello World', true, true);
+
+        $this->assertEquals("^XA\n^FO0,0^GB100,10,3,B,0^FS\n^FO10,2.5\n^FH^FDHello World^FS\n^XZ\n", $this->getZpl());
+    }
+
     #[Test]
     public function drawCellWithEspecialCharacters(): void
     {