Fix deprecations on 8.19 and 8.20, update CI #26

Job	Run time
build (mathcomp/mathcomp-dev:coq-dev)	2m 43s
build (mathcomp/mathcomp:2.2.0-coq-8.19)	12m 53s
build (mathcomp/mathcomp:2.1.0-coq-8.18)	21m 33s
build (mathcomp/mathcomp:2.0.0-coq-8.17)	22m 31s
build (mathcomp/mathcomp:1.17.0-coq-8.17)	14m 44s
build (mathcomp/mathcomp:1.16.0-coq-8.17)	14m 36s
build (mathcomp/mathcomp:1.15.0-coq-8.16)	16m 12s
build (mathcomp/mathcomp:1.14.0-coq-8.15)	16m 6s
build (mathcomp/mathcomp:1.13.0-coq-8.15)	16m 21s
build (mathcomp/mathcomp:1.12.0-coq-8.14)	17m 23s
	2h 35m 2s

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