chore: refactor animation to remove dep

Author: apiad

src/tesserax/animation.py

@@ -8,7 +8,6 @@
 import io
 import base64
 from pathlib import Path
-import imageio
 
 
 from .base import IVisual, Text, Polyline
@@ -822,6 +821,7 @@ def save(self, dest: str | Path | io.BytesIO, format: str | None = None, **kwarg
         if not self._frames:
             return
 
+        import imageio
         from PIL import Image
 
         # Convert PNG bytes to Pillow images for ImageIO