update changelog for stable version 0.21.1 #72

Job	Run time
Prepare Release	7s
Build Linux (ubuntu-22.04-arm, aarch64-unknown-linux-gnu)	7m 45s
Build Linux (ubuntu-22.04, x86_64-unknown-linux-gnu)	6m 8s
Build Windows (x86_64-pc-windows-msvc)	8m 0s
Build Windows (aarch64-pc-windows-msvc)	8m 8s
Finalize Release	6s
Update CDN URLs in latest.json	7s
	30m 21s

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