Fix compatibility with PyPy #165

Job	Run time
publish / Load build targets	4s
publish / Build source distribution	1m 2s
publish / Build cp*-manylinux_i686 wheels	7m 22s
publish / Build cp*-manylinux_x86_64 wheels	2m 48s
publish / Build cp*-manylinux_aarch64 wheels	2m 41s
publish / Build pp39-manylinux_x86_64 wheels	27s
publish / Build cp*-macosx_x86_64 wheels	9m 11s
publish / Build cp*-macosx_arm64 wheels	3m 15s
publish / Build pp39-macosx_x86_64 wheels	30s
publish / Build cp*-win32 wheels	7m 46s
publish / Build cp*-win_amd64 wheels	6m 41s
publish / Build pp39-win_amd64 wheels	57s
publish / Upload	0s
	42m 44s

Provide feedback