chore(deps): update dependency gitlab-org/labkit to v2.20.5

See merge request !1609

go-test v0.2.0 replaces its scalar integration_service / integration_service_alias
inputs with a single integration_services array (list of GitLab `services` maps),
enabling multiple service containers (e.g. Postgres + Redis) on one integration job.

Mirror that in golang-build: replace the two scalar inputs with an
integration_services array input and forward it (unquoted, so GitLab injects the
array) into go-test, bumping the go-test pin v0.1.1 -> v0.2.0.

Note: this is a breaking input change to golang-build (the integration_service /
integration_service_alias inputs are removed). No known consumer sets them.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

feat(golang-build): forward integration_services array to go-test

See merge request !1602

## [4.15.0](https://gitlab.com/gitlab-com/gl-infra/common-ci-tasks/-/compare/...) (2026-06-17)

### Features

* **golang-build:** forward integration_services array to go-test ([33069e3a](33069e3a))

### Dependencies

* **deps:** update dependency gitlab-org/labkit to v2.20.5 ([e9c9c2b5](e9c9c2b5))