canary: bump golang from 1.21rc3 to 1.21rc4 in /dependabot/docker/go #66

Job	Run time
CI matrix / Assert PR branch is ahead	7s
Makefile / Assert PR branch is ahead	5s
Makefile / Build codebase using Makefile quick recipe	38s
Makefile / Lint codebase using Makefile	1m 1s
Makefile / Build codebase using Makefile all recipe	0s
CI matrix / Lint codebase (go-ci-oldstable, false)	33s
CI matrix / Lint codebase (go-ci-stable, false)	30s
CI matrix / Lint codebase (go-ci-unstable, true)	32s
CI matrix / Build codebase (go-ci-oldstable, false)	26s
CI matrix / Build codebase (go-ci-stable, false)	28s
CI matrix / Build codebase (go-ci-unstable, true)	32s
CI matrix / Run tests (go-ci-oldstable, false)	27s
CI matrix / Run tests (go-ci-stable, false)	27s
CI matrix / Run tests (go-ci-unstable, true)	28s
CI matrix / Optional Linting / Assert PR branch is ahead	7s
CI matrix / Optional Linting / Lint codebase using optional linters (go-ci-oldstable, true)	30s
CI matrix / Optional Linting / Lint codebase using optional linters (go-ci-stable, true)	36s
CI matrix / Optional Linting / Lint codebase using optional linters (go-ci-unstable, true)	37s
	8m 4s

Provide feedback