remove html4 writer, since its deprecated with newer sphinx versions

doc/conf.py

@@ -213,15 +213,9 @@
 # see here https://github.com/phn/pytpm/issues/3#issuecomment-12133978
 numpydoc_show_class_members = False
 
-# path to bibtex_bibfiles
+# path to bibtex-bibfiles
 bibtex_bibfiles = ['bib/elephant.bib']
 
-# A fix for Alabaster theme for no space between a citation reference
-# and citation text
-# https://github.com/sphinx-doc/sphinx/issues/6705#issuecomment-536197438
-html4_writer = True
-
-
 # -- Options for LaTeX output --------------------------------------------
 
 latex_elements = {