Fix optimize=2/3 crash when using Python API

The jpg_quality and png_quality options default to None in the pydantic
model, but the fallback check only handled == 0. This caused a TypeError
when calling ocrmypdf.ocr() with optimize >= 2 without explicitly
setting quality values. Fixes #1641.

src/ocrmypdf/optimize.py

@@ -681,9 +681,9 @@ def optimize(
         safe_symlink(input_file, output_file)
         return output_file
 
-    if options.jpg_quality == 0:
+    if not options.jpg_quality:
         options.jpg_quality = DEFAULT_JPEG_QUALITY if options.optimize < 3 else 40
-    if options.png_quality == 0:
+    if not options.png_quality:
         options.png_quality = DEFAULT_PNG_QUALITY if options.optimize < 3 else 30
 
     with Pdf.open(input_file) as pdf: