Fix fpdf text mode in multi-page renderer; add v17.2.0 release notes

The previous fix (e62e73e4) only corrected text_rendering_mode →
text_mode in the single-page Fpdf2PdfRenderer, but the main OCR
pipeline uses Fpdf2MultiPageRenderer which still had the old
attribute name. Since fpdf2 has no text_rendering_mode property,
setting it silently created a no-op attribute while text_mode stayed
at FILL — so 3 Tr (invisible text) was never emitted.

Fixes #1631, #1632

src/ocrmypdf/fpdf_renderer/renderer.py

@@ -802,9 +802,9 @@ class Fpdf2MultiPageRenderer:
 
         # Set text mode for invisible text
         if self.invisible_text:
-            pdf.text_rendering_mode = TextMode.INVISIBLE
+            pdf.text_mode = TextMode.INVISIBLE
         else:
-            pdf.text_rendering_mode = TextMode.FILL
+            pdf.text_mode = TextMode.FILL
 
         # Shared font registration across all pages
         shared_registered_fonts: dict[str, str] = {}