Update CHANGELOG for v0.20.4 release #1785

Job	Run time
Generate semantic release version using git-describe-semver	6s
Build stable Alpine x64 image using Makefile	54s
Build oldstable Alpine x86 image using Makefile	59s
Build oldstable Alpine x64 image using Makefile	1m 7s
Build oldstable cgo-mingw-w64 x64 image using Makefile	1m 38s
Build stable Alpine x86 image using Makefile	1m 3s
Build stable image using Makefile	1m 53s
Build unstable Alpine x64 image using Makefile	1m 0s
Build unstable Alpine x86 image using Makefile	57s
Build oldstable cgo-mingw-w64 x86 image using Makefile	1m 43s
Build oldstable image using Makefile	1m 45s
Build stable cgo-mingw-w64 x64 image using Makefile	1m 26s
Build stable cgo-mingw-w64 x86 image using Makefile	1m 40s
Build stable mirror images using Makefile	44s
Build unstable cgo-mingw-w64 x64 image using Makefile	1m 53s
Build unstable image using Makefile	1m 39s
Build unstable cgo-mingw-w64 x86 image using Makefile	1m 47s
	22m 14s

Provide feedback