chore: Update image builds with new tags

[Venefilyn]

We used to use :latest tags like this

• ghcr.io/oamg/convert2rhel-centos7:latest
• ghcr.io/oamg/convert2rhel-centos8:latest
• ghcr.io/oamg/convert2rhel-centos9:latest

but now we unify them with

• ghcr.io/oamg/convert2rhel-centos:7
• ghcr.io/oamg/convert2rhel-centos:8
• ghcr.io/oamg/convert2rhel-centos:9

Jira Issues:

-

Checklist

• [ ] PR has been tested manually in a VM (either author or reviewer)
• [ ] Jira issue has been made public if possible
• [ ] [RHELC-] or [HMS-] is part of the PR title
• [ ] GitHub label has been added to help with Release notes
• [ ] PR title explains the change from the user's point of view
• [ ] Code and tests are documented properly
• [ ] The commits are squashed to as few commits as possible (without losing data)
• [ ] When merged: Jira issue has been updated to Release Pending if relevant

[has-bot]

This PR does not require integration tests to be run.

---

Comment generated by an automation.

Log | Bot Usage

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 96.51%. Comparing base (836e9ba) to head (ffdffa2). Report is 5 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1393 +/- ## ======================================= Coverage 96.51% 96.51% ======================================= Files 71 71 Lines 5077 5077 Branches 883 883 ======================================= Hits 4900 4900 Misses 98 98 Partials 79 79 ``` | [Flag](https://app.codecov.io/gh/oamg/convert2rhel/pull/1393/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=oamg) | Coverage Δ | | |---|---|---| | [centos-linux-7](https://app.codecov.io/gh/oamg/convert2rhel/pull/1393/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=oamg) | `92.01% <ø> (ø)` | | | [centos-linux-8](https://app.codecov.io/gh/oamg/convert2rhel/pull/1393/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=oamg) | `92.88% <ø> (ø)` | | | [centos-linux-9](https://app.codecov.io/gh/oamg/convert2rhel/pull/1393/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=oamg) | `92.92% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=oamg#carryforward-flags-in-the-pull-request-comment) to find out more.

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