Bump version to 20.2.0 #3189

Job	Run time
Unit tests (ubuntu-20.04, 1.21)	5m 56s
Build (ubuntu-latest, x86_64-unknown-linux-gnu, amd64)	2m 11s
Unit tests (ubuntu-22.04, 1.21)	5m 50s
Integration tests (ubuntu-20.04, 1.21, .CLI.)	15m 1s
Integration tests (ubuntu-20.04, 1.21, ^Test(([^C])\|(C[^L])\|(CL[^I])).*$)	12m 47s
Build (ubuntu-latest, aarch64-unknown-linux-gnu, arm64)	2m 57s
Integration tests (ubuntu-22.04, 1.21, .CLI.)	14m 29s
Build (macos-latest, x86_64-apple-darwin, amd64)	6m 19s
Integration tests (ubuntu-22.04, 1.21, ^Test(([^C])\|(C[^L])\|(CL[^I])).*$)	12m 38s
Build (macos-latest, aarch64-apple-darwin, arm64)	4m 29s
Build (windows-latest, x86_64-pc-windows-gnu, amd64)	7m 13s
	1h 29m 50s

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