main/postmarketos-ui-*: add explicit networkmanager-openrc dependency (MR 3111)

This should be reverted when this Alpine issue has been closed:
https://gitlab.alpinelinux.org/alpine/aports/-/issues/13778

sxmo-common already had this for some reason.

[ci:ignore-count]
[ci:skip-build] Already built successfuly on CI in MR