[CI] Update Nix toolbox #287

Job	Run time
coq	1m 1s
stdlib	3m 25s
coq-elpi	59s
hierarchy-builder	59s
mathcomp-ssreflect	3m 6s
mathcomp-finmap	1m 37s
mathcomp-fingroup	1m 57s
mathcomp-bigenough	1m 30s
mathcomp-algebra	3m 17s
mathcomp-classical	2m 45s
mathcomp-solvable	2m 49s
multinomials	2m 3s
mathcomp-reals	2m 15s
mathcomp-field	4m 23s
mathcomp-experimental-reals	1m 55s
mathcomp-reals-stdlib	1m 35s
mathcomp-character	2m 30s
mathcomp-real-closed	2m 37s
mathcomp-analysis	10m 1s
mathcomp	1m 43s
odd-order	8m 35s
mathcomp-analysis-stdlib	10m 28s
	1h 11m 30s

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