Drop deprecated `nursery` rule group

[T-256]

Summary

Resolves https://github.com/astral-sh/ruff/issues/7992

[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #10172 will not alter performance

_{Comparing T-256:drop-nursery (53355b8) with ruff-0.5 (25efb82)}

Summary

✅ 30 untouched benchmarks

[github-actions[bot]]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

Formatter (stable)

✅ ecosystem check detected no format changes.

Formatter (preview)

✅ ecosystem check detected no format changes.

[zanieb]

Thank you! It looks like this didn't make it into v0.3.0 and will need to be considered for v0.4.0 instead