ci: Sprite::rotate: use 360 - deg instead of negative deg

Author: vincent4vx

.github/workflows/build.yml

@@ -17,9 +17,6 @@ jobs:
         steps:
             - uses: actions/checkout@v2
 
-            - name: Remove system libgd & PHP
-              run: sudo apt-get remove -y libgd3 'php*'
-
             - name: Install PHP
               uses: shivammathur/setup-php@v2
               with:

src/Sprite/Sprite.php

@@ -161,7 +161,7 @@ public function rotate(int $rotation): self
         assert($gd !== false);
 
         // GD rotates counter-clockwise, so negate the rotation
-        $gd = imagerotate($gd, -$rotation * 90, 0);
+        $gd = imagerotate($gd, 360 - $rotation * 90, 0);
         assert($gd !== false);
 
         // 180deg rotation: only change offsets, no need to rescale