Docs action often errors on downloading notebooks

[lauramurgatroyd]

Description

https://github.com/TomographicImaging/CIL/actions/runs/27620834774/job/81668953345

Traceback (most recent call last):
  File "/home/runner/work/CIL/CIL/docs/./mkdemos.py", line 67, in <module>
    notebooks_load = download_notebooks(NOTEBOOKS_load_links)
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/runner/work/CIL/CIL/docs/./mkdemos.py", line 62, in download_notebooks
    with urlopen(url) as response:
         ^^^^^^^^^^^^
  File "/home/runner/miniconda3/envs/test/lib/python3.12/urllib/request.py", line 215, in urlopen
    return opener.open(url, data, timeout)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/runner/miniconda3/envs/test/lib/python3.12/urllib/request.py", line 515, in open
    response = self._open(req, data)
               ^^^^^^^^^^^^^^^^^^^^^
  File "/home/runner/miniconda3/envs/test/lib/python3.12/urllib/request.py", line 532, in _open
    result = self._call_chain(self.handle_open, protocol, protocol +
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/runner/miniconda3/envs/test/lib/python3.12/urllib/request.py", line 492, in _call_chain
    result = func(*args)
             ^^^^^^^^^^^
  File "/home/runner/miniconda3/envs/test/lib/python3.12/urllib/request.py", line 1392, in https_open
    return self.do_open(http.client.HTTPSConnection, req,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/runner/miniconda3/envs/test/lib/python3.12/urllib/request.py", line 1347, in do_open
    raise URLError(err)
urllib.error.URLError: <urlopen error [Errno 110] Connection timed out>
make: *** [Makefile:32: dirhtml] Error 1

Environment

import cil, sys
print(cil.version.version, cil.version.commit_hash, sys.version, sys.platform)