Merge branch 'protos' into make-headers-gpl-compliant #398

Job	Run time
Build MDANSE and run tests on ubuntu-20.04	3m 15s
Build MDANSE and run tests on ubuntu-20.04	3m 19s
Build MDANSE and run tests on ubuntu-20.04	2m 44s
Build MDANSE and run tests on ubuntu-20.04	3m 13s
Build MDANSE and run tests on windows-2019	5m 25s
Build MDANSE and run tests on windows-2019	3m 28s
Build MDANSE and run tests on windows-2019	4m 4s
Build MDANSE and run tests on windows-2019	4m 8s
Build MDANSE and run tests on macOS-11	5m 2s
Build MDANSE and run tests on macOS-11	4m 58s
Build MDANSE and run tests on macOS-11	5m 6s
Build MDANSE and run tests on macOS-11	5m 29s
	50m 11s

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