Update uv in RTD config

[danielhollas]

See also discussion in aiidateam/aiida-core#6685.
Includes a fix from aiidateam/aiida-core#6700

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.41%. Comparing base (0ebfa1c) to head (80ebc2a).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #660   +/-   ##
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  Coverage   83.41%   83.41%           
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  Files          17       17           
  Lines        3581     3581           
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  Hits         2987     2987           
  Misses        594      594           

Flag	Coverage Δ
python-3.11	83.41% <ø> (ø)
python-3.9	83.44% <ø> (ø)

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[danielhollas]

Unlike with uv sync which we use in aiida-core, here we can manually specify the target virtual environment with uv pip install. This in turn let's us use the sphinx section below instead of specifying the build command manually.

[danielhollas]

I went ahead and merged this since the RTD build already started failing in other PR due to a missing sphinx.configuration key (see https://about.readthedocs.com/blog/2024/12/deprecate-config-files-without-sphinx-or-mkdocs-config/)