Merge pull request #444 from isuruf/cython3 #264

Job	Run time
build (Debug, yes, 3.11, yes, ubuntu-20.04, gcc)	5m 5s
build (Debug, yes, 3.10, yes, ubuntu-20.04, gcc)	6m 33s
build (Debug, yes, 3.9, yes, ubuntu-20.04, gcc)	6m 52s
build (Release, 3.7, yes, ubuntu-20.04, gcc)	6m 46s
build (Release, 3.7, yes, gmpxx, no, ubuntu-20.04, gcc)	8m 49s
build (Release, 3.8, yes, ubuntu-20.04, gcc)	9m 39s
build (Release, yes, 3.8, ubuntu-20.04, gcc)	7m 52s
build (Release, 3.9, yes, ubuntu-20.04, gcc)	11m 5s
build (Release, 3.9, yes, flint, yes, ubuntu-20.04, gcc)	8m 26s
build (Debug, 3.8, yes, yes, ubuntu-20.04, clang)	4m 28s
build (Release, 3.7, yes, ubuntu-20.04, clang)	7m 18s
build (Debug, 3.10, yes, 14, yes, boostmp, -k "not integer_nthroot", ubuntu-22.04, deb http://apt...	11m 48s
build (Debug, 3.7, yes, 5, macos-latest, clang)	13m 10s
build (Release, 3.9, no, macos-latest, clang)	10m 41s
build (Debug, 3.7, no, macos-latest, gcc)	10m 55s
build (Release, 3.8, macos-latest, gcc)	10m 14s
build (Release, 3.8, ubuntu-20.04, yes, yes, yes, yes, yes, flint, yes, gcc)	8m 43s
	2h 28m 24s

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