sysutils/stackit: Update 0.56.0 => 0.59.0

Changelogs:

• https://github.com/stackitcloud/stackit-cli/releases/tag/v0.57.0
• https://github.com/stackitcloud/stackit-cli/releases/tag/v0.58.0
• https://github.com/stackitcloud/stackit-cli/releases/tag/v0.59.0

PR: 294408
Reported by: Robert Gogolok <gogolok@gmail.com> (maintainer)
Approved by: osa, vvd (mentors)
MFH: 2026Q2