Update CHANGELOG for v0.5.5 release #598

Job	Run time
CI matrix / Assert PR branch is ahead	5s
Makefile / Assert PR branch is ahead	5s
CI matrix / Lint codebase (go-ci-oldstable, false)	3m 17s
CI matrix / Evaluate loopvar scoping changes	3m 8s
CI matrix / Lint codebase (go-ci-stable, false)	3m 51s
CI matrix / Build codebase (go-ci-oldstable, false)	3m 20s
CI matrix / Lint codebase (go-ci-unstable, true)	3m 53s
CI matrix / Build codebase (go-ci-stable, false)	3m 19s
CI matrix / Build codebase (go-ci-unstable, true)	3m 14s
CI matrix / Run tests (go-ci-oldstable, false)	2m 58s
CI matrix / Run tests (go-ci-stable, false)	3m 3s
CI matrix / Run tests (go-ci-unstable, true)	3m 39s
Makefile / Build codebase using Makefile all recipe	0s
Makefile / Build codebase using Makefile quick recipe	3m 40s
Makefile / Lint codebase using Makefile	0s
CI matrix / Optional Linting / Assert PR branch is ahead	5s
CI matrix / Optional Linting / Lint codebase using optional linters (go-ci-oldstable, true)	3m 24s
CI matrix / Optional Linting / Lint codebase using optional linters (go-ci-stable, true)	3m 28s
CI matrix / Optional Linting / Lint codebase using optional linters (go-ci-unstable, true)	5m 22s
	49m 51s

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