DEP: drop `[isolated]` extra #1085

Job	Run time
Python 3.10 (isolated deps)	12s
Python 3.13 (isolated deps)	22s
Python 3.10 on ubuntu-latest (free-threading: false)	13s
Python 3.11 on ubuntu-latest (free-threading: false)	11s
Python 3.12 on ubuntu-latest (free-threading: false)	18s
Python 3.13 on ubuntu-latest (free-threading: false)	20s
Python 3.10 on macos-latest (free-threading: false)	12s
Python 3.11 on macos-latest (free-threading: false)	13s
Python 3.12 on macos-latest (free-threading: false)	13s
Python 3.13 on macos-latest (free-threading: false)	13s
Python 3.10 on windows-latest (free-threading: false)	42s
Python 3.11 on windows-latest (free-threading: false)	36s
Python 3.12 on windows-latest (free-threading: false)	39s
Python 3.13 on windows-latest (free-threading: false)	1m 20s
Python 3.13 on ubuntu-latest (free-threading: true)	48s
docs	17s
type check (3.10)	12s
type check (3.12)	14s
	7m 15s

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