fix(deps): drop stale numpy<2 pin from the docs extra

[FBumann]

Note

This PR was generated by AI (Claude Code), reviewed by @FBumann.

Installing linopy[docs,benchmarks] is currently unresolvable:

× No solution found when resolving dependencies:
╰─▶ Because linopy[benchmarks] depends on numpy==2.4.6 and linopy[docs]
    depends on numpy<2, we can conclude that linopy[benchmarks] and
    linopy[docs] are incompatible.

The numpy<2 pin in the docs extra dates from the numpy 2.0 transition (e2f95f3, June 2024) and is obsolete: the core dependency is unpinned, the benchmarks extra pins numpy 2.4.6, and the docs stack (matplotlib 3.11, sphinx 9) supports numpy 2. This drops the pin; uv pip compile with both extras now resolves (numpy 2.4.6).

🤖 Generated with Claude Code

[codspeed-hq]

Merging this PR will not alter performance

✅ 173 untouched benchmarks
⏩ 173 skipped benchmarks¹

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_{Comparing fix/docs-numpy-pin (87b1f20) with master (2afe5d0)}

Footnotes

1. 173 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩