setup.py: update default mupdf to 1.26.10.

Author: julian-smith-artifex-com

setup.py

@@ -1269,7 +1269,7 @@ def sdist():
 # PyMuPDF version.
 version_p = '1.26.5'
 
-version_mupdf = '1.26.7'
+version_mupdf = '1.26.10'
 
 # PyMuPDFb version. This is the PyMuPDF version whose PyMuPDFb wheels we will
 # (re)use if generating separate PyMuPDFb wheels. Though as of PyMuPDF-1.24.11