Remove deprecated tests_require #466

Job	Run time
coverage-test	8m 53s
fuzzing-test	4m 33s
generic-build-test (ubuntu-18.04, gcc)	7m 7s
coverity-test	0s
generic-build-test (ubuntu-18.04, clang)	6m 24s
generic-build-test (ubuntu-20.04, gcc)	6m 49s
generic-build-test (ubuntu-20.04, clang)	5m 46s
generic-build-test (fedora-30, gcc)	7m 19s
generic-build-test (fedora-30, clang)	6m 33s
generic-build-test (opensuse-leap, gcc)	7m 3s
generic-build-test (opensuse-leap, clang)	6m 16s
generic-build-test (ubuntu-22.04, gcc)	44m 26s
	1h 51m 9s

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