Old version of doxygen used for the documentation

[albert-github]

For the website of GUDHI https://gudhi.inria.fr/doc/latest/index.html#we see that doxygen version 1.9.1 is used:

The current doxygen version is 1.100.0 and furthermore in the pull requests #635 / #637 that signal that some aspects don't work with doxygen 1.9.1 but require at least doxygen 1.9.3.