Upgrade mimalloc. #498

Job	Run time
docs	1m 1s
host=ubuntu-22.04 cmd=cli target=x86_64-linux-gnu mode=release	5m 0s
host=ubuntu-22.04 cmd=cli target=x86_64-selinux-gnu mode=release	4m 24s
host=macos-12 cmd=cli target=x86_64-macos-none mode=release	5m 32s
host=macos-14 cmd=cli target=aarch64-macos-none mode=release	2m 0s
host=windows-2022 cmd=cli target=x86_64-windows-gnu mode=release	5m 53s
host=windows-2022 cmd=lib target=x86_64-windows-gnu mode=release	4m 39s
host=windows-2022 cmd=lib target=x86_64-windows-msvc mode=release	2m 7s
host=ubuntu-22.04 cmd=web-lib target=wasm32-freestanding mode=release	1m 51s
host=ubuntu-22.04 cmd=cli target=wasm32-wasi mode=release	1m 58s
host=ubuntu-22.04 cmd=lib target=x86_64-linux-gnu mode=release	3m 30s
host=macos-12 cmd=lib target=x86_64-macos-none mode=release	3m 50s
host=macos-14 cmd=lib target=aarch64-macos-none mode=release	2m 22s
Release	12s
	44m 19s

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