Readme: mention alternative composer approach (#76) #204

Job	Run time
checks	18s
tests (7.2, prefer-lowest, ubuntu-latest)	9s
tests (7.2, prefer-lowest, windows-latest)	34s
tests (7.2, prefer-stable, ubuntu-latest)	17s
tests (7.2, prefer-stable, windows-latest)	30s
tests (7.3, prefer-lowest, ubuntu-latest)	10s
tests (7.3, prefer-lowest, windows-latest)	29s
tests (7.3, prefer-stable, ubuntu-latest)	13s
tests (7.3, prefer-stable, windows-latest)	35s
tests (7.4, prefer-lowest, ubuntu-latest)	9s
tests (7.4, prefer-lowest, windows-latest)	30s
tests (7.4, prefer-stable, ubuntu-latest)	13s
tests (7.4, prefer-stable, windows-latest)	31s
tests (8.0, prefer-lowest, ubuntu-latest)	8s
tests (8.0, prefer-lowest, windows-latest)	28s
tests (8.0, prefer-stable, ubuntu-latest)	9s
tests (8.0, prefer-stable, windows-latest)	33s
tests (8.1, prefer-lowest, ubuntu-latest)	9s
tests (8.1, prefer-lowest, windows-latest)	34s
tests (8.1, prefer-stable, ubuntu-latest)	10s
tests (8.1, prefer-stable, windows-latest)	31s
tests (8.2, prefer-lowest, ubuntu-latest)	16s
tests (8.2, prefer-lowest, windows-latest)	29s
tests (8.2, prefer-stable, ubuntu-latest)	16s
tests (8.2, prefer-stable, windows-latest)	29s
tests (8.3, prefer-lowest, ubuntu-latest)	9s
tests (8.3, prefer-lowest, windows-latest)	24s
tests (8.3, prefer-stable, ubuntu-latest)	10s
tests (8.3, prefer-stable, windows-latest)	26s
	9m 59s

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