https://pagure.io/centos-infra/issue/1614

Please add a new tag for the Proposed Updates SIG:

```
$sig = sig-proposed-updates
$version = 9s, 10s
$project = packages
$version = main
```

leading to `proposed-updates

s-packages-main-

`. This will be used to hold proposed updates submitted as MRs to CentOS Stream repos. cc @dcavalca who's the SIG sponsor, @jonathanspw the SIG chair.

We need the following macros set for the build:

```
%dist .~proposed.el9
```

```
%dist .~proposed.el10
```

the tilde is to make sure any official build with the same release number would sort higher than the proposed-updates build

e.g.

```
$ rpmdev-vercmp 1.0.0-2.el9 1.0.0-2.~proposed.el9
1.0.0-2.el9 > 1.0.0-2.~proposed.el9
```
This should inherit the following external repos for c9s:

```
centos9s-baseos
centos9s-appstream
centos9s-crb
centos9s-buildroot
```

and for c10s:

```
centos10s-baseos
centos10s-appstream
centos10s-crb
centos10s-buildroot
```

The vendor string should be set to `CentOS Proposed Updates SIG`.

We also need a GitLab group under https://gitlab.com/CentOS/ - maybe ProposedUpdates - and for members, make jonathanspw and salimma sponsors

And a signing key

Thanks!