v2.2.1 — CMake-based necpp v2.2.0 engine, build fixes #20

Job	Run time
Build necpp source distribution	2m 32s
Build necpp wheels on macos-arm	4m 50s
Build necpp wheels on linux	6m 31s
upload_pypi	1m 28s
Test necpp on linux	10s
	15m 31s

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