Add ConvNeXtV2 backbone #170

Job	Run time
build (ubuntu-latest, 3.7, 1.9.0+cpu, 0.10.0+cpu, https://download.pytorch.org/whl/torch_stable.h...	5m 31s
build (ubuntu-latest, 3.9, 1.13.1+cpu, 0.14.1+cpu, https://download.pytorch.org/whl/torch_stable....	29m 50s
build (ubuntu-latest, 3.10, 2.1.0+cpu, 0.16.0+cpu, https://download.pytorch.org/whl/torch_stable....	10m 9s
build (macos-latest, 3.7, 1.9.0, 0.10.0, https://download.pytorch.org/whl/torch_stable.html, true)	12m 37s
build (macos-latest, 3.9, 1.13.1, 0.14.1, https://download.pytorch.org/whl/torch_stable.html, tru...	20m 8s
build (macos-latest, 3.10, 2.1.0, 0.16.0, https://download.pytorch.org/whl/torch_stable.html, true)	18m 17s
build (windows-latest, 3.9, 1.13.1+cpu, 0.14.1+cpu, https://download.pytorch.org/whl/torch_stable...	8m 21s
	1h 44m 53s

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