Ensure sphinx API docs have copyright date updated from main build logic

[bdbaddog]

Describe the bug
The copyright date is hard coded to 2022 in docs/sphinx/conf.py

We should update the logic so it uses the auto-generated copyright date in our main build logic

[mwichmann]

Related only in that it also goes in conf.py - the separate discussion about instructing Sphinx to generate lines to fetch fonts from a CDN:

diff --git a/doc/sphinx/conf.py b/doc/sphinx/conf.py
index 5b9cbb0d2..c234fbdcd 100644
--- a/doc/sphinx/conf.py
+++ b/doc/sphinx/conf.py
@@ -104,6 +104,10 @@ version_parts = __version__.split('.')
 major, minor, patch = version_parts[0:3]
 version = '.'.join([major, minor,patch])
 
+html_css_files = [
+    "https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.1.1/css/all.min.css"
+]
+
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
 #

I'm not sure right at the top is the right place to put this stanza, and it should come with a comment, but that seems to generate the desired bits... it adds this line to all the API-doc index.html files - I presume that's sufficient for purpose?

    <link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.1.1/css/all.min.css" />

It doesn't seem to omit anything from the generated files. My knowledge of this is now exhausted...