Try to fix QR code testing issue

tests/Image/QrCodeTest.php

@@ -142,14 +142,20 @@ public function testWrite()
 		$this->assertFileExists($file);
 		$this->assertFileEquals(static::FIXTURES . '/test.png', $file);
 
-		$qr->write($file = static::TMP . '/test.gif');
-		$this->assertFileExists($file);
-		$this->assertFileEquals(static::FIXTURES . '/test.gif', $file);
-
 		$qr->write($file = static::TMP . '/test.webp');
 		$this->assertFileExists($file);
 		$this->assertFileEquals(static::FIXTURES . '/test.webp', $file);
 
+		// test GIF by comparing the output dynamically to avoid issues
+		// with different libraries/library versions in CI
+		$fixture      = static::FIXTURES . '/test.gif';
+		$expectedGif = $this->imageContent(imagecreatefromgif($fixture));
+
+		$qr->write($file = static::TMP . '/test.gif');
+		$this->assertFileExists($file);
+		$actualGif = $this->imageContent(imagecreatefromgif($file));
+		$this->assertSame($expectedGif, $actualGif);
+
 		// test JPEG by comparing the output dynamically to avoid issues
 		// with different libraries/library versions in CI
 		$fixture      = static::FIXTURES . '/test.jpg';