Update os-image-server to v2.1.3 (release-1.3)

⚠️

This is a "dummy" tag update, needed because I created the release-2.1 branch in os-image-server repo, but **the 2.1.2 tag had been created on main before that, and should not be used from Sylva 1.3.

This MR will allow to have clean backport state for os-image-server to backport #2166 (closed) in Sylva 1.3.

The diff is empty:

sylva-elements/helm-charts/os-image-server$ git diff 2.1.1..2.1.3
sylva-elements/helm-charts/os-image-server$ 

---

Package	Update	Change
https://gitlab.com/sylva-projects/sylva-elements/helm-charts/os-image-server.git	patch	2.1.1 -> 2.1.3