Don't silently drop pil_kwargs for non-Pillow-based formats.

Author: anntzer

lib/mplcairo/base.py

@@ -173,7 +173,7 @@ def tostring_rgba_minimized(self):  # Needed for MixedModeRenderer.
 def _check_print_extra_kwargs(*,
         # These arguments are already taken care of by print_figure().
         dpi=72, facecolor=None, edgecolor=None, orientation="portrait",
-        dryrun=False, bbox_inches_restore=None, pil_kwargs=None):
+        dryrun=False, bbox_inches_restore=None):
     pass