Bump version to 0.3.0 #441

Job	Run time
macos-x86_64	14m 3s
macos-aarch64	11m 34s
sdist	7m 12s
linux (x86_64-unknown-linux-gnu)	8m 6s
windows (x86_64-pc-windows-msvc, x64)	13m 58s
windows (i686-pc-windows-msvc, x86)	13m 24s
linux-arm (aarch64-unknown-linux-gnu, aarch64, -e JEMALLOC_SYS_WITH_LG_PAGE=16)	8m 48s
linux (i686-unknown-linux-gnu)	11m 44s
linux-arm (armv7-unknown-linux-gnueabihf, armv7)	10m 15s
linux-arm (arm-unknown-linux-musleabihf, arm)	7m 51s
linux-powerpc (powerpc64le-unknown-linux-gnu, ppc64le)	8m 40s
linux-s390x (s390x-unknown-linux-gnu, s390x)	12m 5s
linux-powerpc (powerpc64-unknown-linux-gnu, ppc64)	8m 34s
musllinux (x86_64-unknown-linux-musl)	8m 3s
musllinux (i686-unknown-linux-musl)	7m 40s
musllinux-cross (aarch64-unknown-linux-musl, aarch64, -e JEMALLOC_SYS_WITH_LG_PAGE=16)	9m 35s
musllinux-cross (armv7-unknown-linux-musleabihf, armv7)	8m 16s
musllinux-cross (powerpc64le-unknown-linux-musl, ppc64le, nightly)	6m 42s
	2h 56m 30s

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