fix(deps): update docker:20.10.21-dind docker digest to 7b7ef88 (renovate-bot/renovate-runner!1055)

mentioned in merge request pipeline-components/org/renovate!138 (merged)

mentioned in merge request kubitus-project/renovate-runner!91 (closed)

mentioned in merge request kubitus-project/renovate-runner!92 (closed)

mentioned in merge request kubitus-project/renovate-runner!93 (closed)

mentioned in merge request kubitus-project/renovate-runner!94 (closed)

mentioned in merge request zerok/docker-cookiecutter!14 (merged)

mentioned in merge request kubitus-project/renovate-runner!95 (closed)

mentioned in merge request kubitus-project/renovate-runner!96 (merged)

mentioned in merge request gitlabracadabra/renovate-runner!2 (merged)

mentioned in merge request engmark/renovate!27