Fix PyPDF2 3.0+ compatibility issues in report_py3o

Add compatibility wrapper classes for PdfFileWriter/PdfFileReader
to support both PyPDF2 2.x and 3.x versions.

Changes:
- Add PyPDF2 compatibility classes in report_py3o/models/py3o_report.py
- Create comprehensive documentation in doc/PATCH_PDFWRITER.md
- Support for appendPagesFromReader method for PDF merging

Resolves PyPDF2.errors.DeprecationError: appendPagesFromReader is deprecated
and was removed in PyPDF2 3.0.0. Use append_pages_from_reader instead.

🤖 assisted by claude

odoo-bringout-oca-reporting-engine-report_py3o/report_py3o/models/py3o_report.py

@@ -37,9 +37,21 @@ try:
 except ImportError:
     logger.debug("Cannot import py3o.formats")
 try:
-    from PyPDF2 import PdfFileReader, PdfFileWriter
+    from PyPDF2 import PdfWriter, PdfReader
+    
+    # Create compatibility classes for PyPDF2 3.0+
+    class PdfFileWriter(PdfWriter):
+        def appendPagesFromReader(self, reader, after_page_append=None):
+            return self.append_pages_from_reader(reader, after_page_append)
+    
+    class PdfFileReader(PdfReader):
+        pass
+
 except ImportError:
-    logger.debug("Cannot import PyPDF2")
+    try:
+        from PyPDF2 import PdfFileReader, PdfFileWriter
+    except ImportError:
+        logger.debug("Cannot import PyPDF2")
 
 _extender_functions = {}