Revert alteration at c9480f9 merge of 3.x of doc/conf.py

Compare doc/conf.py after merge at c9480f9 to what it was at 2ee0338.

It loses the modification from sphinx-doc#8716 (merged at 38c6143) and thus
reverts doc/conf.py to former font config using mathpazo.

doc/conf.py

@@ -58,17 +58,6 @@
 latex_logo = '_static/sphinx.png'
 latex_elements = {
     'fontenc': r'\usepackage[LGR,X2,T1]{fontenc}',
-    'fontpkg': r'''
-\usepackage[sc]{mathpazo}
-\usepackage[scaled]{helvet}
-\usepackage{courier}
-\substitutefont{LGR}{\rmdefault}{cmr}
-\substitutefont{LGR}{\sfdefault}{cmss}
-\substitutefont{LGR}{\ttdefault}{cmtt}
-\substitutefont{X2}{\rmdefault}{cmr}
-\substitutefont{X2}{\sfdefault}{cmss}
-\substitutefont{X2}{\ttdefault}{cmtt}
-''',
     'passoptionstopackages': r'''
 \PassOptionsToPackage{svgnames}{xcolor}
 \PassOptionsToPackage{bookmarksdepth=3}{hyperref}% depth of pdf bookmarks
@@ -78,7 +67,6 @@
 \setcounter{tocdepth}{3}%    depth of what is kept from toc file
 \setcounter{secnumdepth}{1}% depth of section numbering
 ''',
-    'fvset': '\\fvset{fontsize=auto}',
     # fix missing index entry due to RTD doing only once pdflatex after makeindex
     'printindex': r'''
 \IfFileExists{\jobname.ind}