AltDSS/DSS C-API and backend 0.15.0b4 #206

Job	Run time
macOS ARM64	32s
Windows x86	1m 40s
Linux x64 (quay.io/pypa/manylinux_2_28_x86_64, 0)	44s
macOS x64	33s
Windows x64	47s
	4m 16s

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