[BUG] Resolving doc dependencies fails in Python 3.10

[daniel-habermann]

Describe the bug
I'm using uv as a dependency manager and noticed that a simple uv sync fails on dev with the following error message:

  × No solution found when resolving dependencies for split (python_full_version < '3.11'):
  ╰─▶ Because the requested Python version (>=3.10, <3.13) does not satisfy Python>=3.11 and sphinx>=8.2.0,<=8.2.3
      depends on Python>=3.11, we can conclude that sphinx>=8.2.0,<=8.2.3 cannot be used.
      And because only the following versions of sphinx are available:
          sphinx<=8.2.0
          sphinx==8.2.1
          sphinx==8.2.2
          sphinx==8.2.3
          sphinx==8.3.0
      and sphinx==8.3.0 was yanked (reason: Bad release), we can conclude that sphinx>=8.2.0 cannot be used.
      And because bayesflow[all] depends on sphinx>=8.2 and your project requires bayesflow[all], we can conclude that
      your project's requirements are unsatisfiable.

      hint: `sphinx` was requested with a pre-release marker (e.g., all of:
          sphinx>8.2.0,<8.2.1
          sphinx>8.2.1,<8.2.2
          sphinx>8.2.2,<8.2.3
          sphinx>8.2.3,<8.3.0
          sphinx>8.3.0,<9.dev0
      ), but pre-releases weren't enabled (try: `--prerelease=allow`)

      hint: The `requires-python` value (>=3.10, <3.13) includes Python versions that are not supported by
      your dependencies (e.g., sphinx>=8.2.0,<=8.2.3 only supports >=3.11). Consider using a more restrictive
      `requires-python` value (like >=3.11).

I could trace this issue back to PR #465 which pins the sphinx dependency to 8.2, which is incompatible with python 3.10. Setting "sphinx ~= 8.1.3" instead of "sphinx ~= 8.2" fixed the issue. Should I make a PR with this change?

To Reproduce
Minimal steps to reproduce the behavior:

1. git checkout dev
2. python3.10 -m venv myenv
3. source myenv/bin/activate
4. pip install -e ".[docs]"

Essentially, the doc dependencies now require python 3.11 while the requires-python is set to >=3.10.

Expected behavior
pip install -e ".[docs]" with python 3.10 should be able to correctly resolve all dependencies.

Environment

• OS: openSUSE Tumbleweed (should be OS independent)
• Python Version: 3.10
• Backend: none
• BayesFlow Version: v2.0.3 dev branch

Minimality

• I verify that my example is minimal, does not rely on third-party packages, and is most likely an issue in BayesFlow.

[vpratz]

Thanks a lot for reporting and investigating. It would be great if you submit the corresponding PR.

[vpratz]

Closed by #495