[main] Makefile: add registry.access.redhat.com to known registries

[thaJeztah]

• Part of [main] RHEL PoC #342

This part should already be fine to merge

[thaJeztah]

Looks like the opensuse package repository is down?

#13 [suse-base 2/3] RUN zypper -n install rpm-build git
#13 9.293 Retrieving repository 'Main Update Repository' metadata [.......error]
#13 10.56 Repository 'Main Update Repository' is invalid.
#13 10.56 [repo-update|http://download.opensuse.org/update/leap/15.6/oss/] Valid metadata not found at specified URL
#13 10.56 History:
#13 10.56  - [|] Error trying to read from 'http://download.opensuse.org/update/leap/15.6/oss/'
#13 10.56  - Location 'http://download.opensuse.org/update/leap/15.6/oss/content' is temporarily unaccessible.
#13 10.56 
#13 10.56 Please check if the URIs defined for this repository are pointing to a valid repository.
#13 10.56 Warning: Skipping repository 'Main Update Repository' because of the above error.
#13 11.05 Retrieving repository 'Update Repository (Non-Oss)' metadata [.......error]
#13 12.33 Warning: Skipping repository 'Update Repository (Non-Oss)' because of the above error.
#13 12.33 Loading repository data...
#13 12.33 Reading installed packages...
#13 12.33 Repository 'Update Repository (Non-Oss)' is invalid.

[thaJeztah]

Yup; "major outage" https://status.opensuse.org

[thaJeztah]

Merging; everything else is green 👍