Download link displays output in browser instead of downloading.

Describe the bug

Adding a downlod role to download a notebook successfully create the download ling in the generated dosc. However clicking on the link simply displays the notebook in the browser instead of downloading the notebook file.

How to Reproduce

========
ls -l docs/notebooks
total 64
-rw-rw-r-- 1 paul paul 326 Dec 9 17:46 index.rst
-rw-rw-r-- 1 paul paul 199 Dec 9 17:52 Manage_Credentials_download.rst
-rw-r--r-- 1 paul paul 6065 Dec 9 17:15 Manage_Credentials.ipynb

=======
cat docs/notebooks/index.rst:
.. _notebooksref:

Note Books

.. toctree::
:maxdepth: 2
:caption: Contents:

Manage_Credentials
Manage_Credentials_download

======
cat docs/notebooks/Manage_Credentials_download.rst
.. _managed_credentials_downloadref:

Manage_Credentials Download

.. only:: builder_html or readthedoc

See :download:Manage Credentials <Manage_Credentials.ipynb>.

Environment Information

sphinx-build --bug-report Please paste all output below into the bug report template text Platform: linux; (Linux-6.0.6-76060006-generic-x86_64-with-debian-11.5) Python version: 3.7.15 (default, Oct 26 2022, 04:14:11) [GCC 10.2.1 20210110]) Python implementation: CPython Sphinx version: 5.3.0 Docutils version: 0.17.1 Jinja2 version: 3.1.2

Sphinx extensions

No response

Additional context

No response

Start with docs/notebooks/index.rst and docs/notebooks/Manage_Credentials_download.rst, then reproduce the behavior with sphinx-build using the reported notebook download role. Check the generated HTML link and browser behavior; done means clicking the link downloads Manage_Credentials.ipynb instead of displaying it.