Maint: Fix app.builder.outdir as Sphinx now using pathlib

[lucyleeow]

CI is failing with sphinx dev with error:
(see: https://dev.azure.com/sphinx-gallery/sphinx-gallery/_build/results?buildId=1368&view=logs&j=18f51a03-7fab-57d7-f724-30d2d83bc222&t=7c53da0f-8616-5987-83c8-9378d265c3e8&l=1124)

ERROR at setup of test_timings ________________________
/usr/share/miniconda/lib/python3.10/site-packages/sphinx/events.py:96: in emit
    results.append(listener.handler(self.app, *args))
sphinx_gallery/docs_resolv.py:471: in embed_code_links
    _embed_code_links(app, gallery_conf, gallery_dir)
sphinx_gallery/docs_resolv.py:324: in _embed_code_links
    doc_resolvers[this_module] = SphinxDocLinkResolver(
sphinx_gallery/docs_resolv.py:146: in __init__
    if doc_url.startswith(('http://',/ 'https://'))/:
E   AttributeError: 'PosixPath' object has no attribute 'startswith'

The above exception was the direct cause of the following exception:
sphinx_gallery/tests/test_full.py:51: in sphinx_app
    return _sphinx_app(tmpdir_factory, 'html')
sphinx_gallery/tests/test_full.py:83: in _sphinx_app
    app.build(False, [])
/usr/share/miniconda/lib/python3.10/site-packages/sphinx/application.py:355: in build
    self.events.emit('build-finished', None)
/usr/share/miniconda/lib/python3.10/site-packages/sphinx/events.py:107: in emit
    raise ExtensionError(__("Handler %r for event %r threw an exception") %
E   sphinx.errors.ExtensionError: Handler <function embed_code_links at 0x7f163d981990> for event 'build-finished' threw an exception (exception: 'PosixPath' object has no attribute 'startswith')

I think sphinx started using pathlib in: sphinx-doc/sphinx#11526

Potentially in future we may want to check if outdir is a Path object (instead of checking if str starts with http..) but have just used str for now.

[larsoner]

Failure looks real and related

https://dev.azure.com/sphinx-gallery/sphinx-gallery/_build/results?buildId=1370&view=logs&j=18f51a03-7fab-57d7-f724-30d2d83bc222&t=7c53da0f-8616-5987-83c8-9378d265c3e8&l=262

I think str(outdir) is a fine fix! Alternatively we could do Path(outdir) and use paths where possible. Whichever is easier I'd go with...

[lucyleeow]

Have just gone with str here. What do you think about moving from os to pathlib in another PR? (bigger job than initially thought, 380 results...)

[lucyleeow]

moving from os to pathlib

It would be a really big job, but I wonder if it would fix things like: #440

[lucyleeow]

merging as CI is green, will consider migrating to pathlib if you support it @larsoner

[larsoner]

Migrating to pathlib could be helpful. I'm not sure if it's more likely to resolve/fix bugs or create new ones. But could ultimately be worthwhile!

[lucyleeow]

create new ones.

The more I think about it, the more I think this is true. I think it is okay to have only some parts of the code use pathlib, I will amend the app.builder.outdir code to use Path as it is cleaner and we probably want to move this way overall.

[lucyleeow]

(In any case should be done when one has the time to fix the resulting bugs...!)