docs/samples/code-printer.py: fixed to work with latest MuPDF.

Specifying complement of a bitmask goes wrong if a new enum value is added to
MuPDF, so we now simply use `pymupdf.TEXTFLAGS_SEARCH`.

docs/samples/code-printer.py

@@ -227,9 +227,11 @@ def code_printer(outfile):
     pages = [doc[i] for i in new_range]  # these are the TOC pages within main PDF
     for item in TOC:  # search for TOC item text to get its rectangle
         for page in pages:
-            rl = page.search_for(item[1], flags=~(pymupdf.TEXT_PRESERVE_LIGATURES | pymupdf.TEXT_PRESERVE_SPANS))
+            rl = page.search_for(item[1], flags=pymupdf.TEXTFLAGS_SEARCH)
             if rl != []:  # this text must be on next page
                 break
+        else:
+            assert 0, f'Cannot find {item[1]=} in {len(pages)=}.'
         rect = rl[0]  # rectangle of TOC item text
         link = {  # make a link from it
             "kind": pymupdf.LINK_GOTO,