fix(epics): handle datetime format in ISOTime UnmarshalJSON

mentioned in commit 17c2b68d

mentioned in merge request gitlab-org/cli!2607

mentioned in merge request gitlab-com/gl-infra/platform/runway/runwayctl!1435 (merged)

mentioned in merge request gitlab-org/terraform-provider-gitlab!2823

mentioned in merge request sickit/token-operator!40

mentioned in merge request gitlab-com/gl-infra/woodhouse!738

mentioned in merge request gitlab-org/release-tools!4633

mentioned in merge request hojerdev/git-sync!72

mentioned in merge request gitlab-com/gl-infra/oncall-robot-assistant!110

mentioned in merge request schober-server/kubernetes/images/gitlab-token-refresher!37

mentioned in merge request fforster/epic-update!44 (merged)

mentioned in merge request gitlab-com/gl-infra/ringctl!405

mentioned in merge request fforster/gitlab-mcp!211 (merged)

mentioned in merge request gitlab-com/gl-infra/autolabels!137 (merged)