Updated libpng to 1.6.46 #528

Job	Run time
macOS 10.10 x86_64	20m 0s
macOS 10.13 x86_64	22m 37s
sdist	24s
macOS 10.15 x86_64	19m 22s
macOS arm64	19m 44s
manylinux2014 and musllinux x86_64	38m 32s
Windows x86	22m 11s
manylinux_2_28 x86_64	18m 33s
Windows AMD64	33m 37s
manylinux2014 and musllinux aarch64	34m 47s
Windows ARM64	11m 6s
manylinux_2_28 aarch64	18m 34s
Upload wheels to scientific-python-nightly-wheels	0s
Upload release to PyPI	0s
	4h 19m 27s

Provide feedback