Scripts, Release: Fix [gitlab_release] regexp

What

Fix illformed regular expression for gitlab_release

Fixes https://gitlab.com/nomadic-labs/tezos/-/issues/698

Why

The regular expression would not work for beta and rc versions

How

Allow -beta and -rc in regular expression

Manually testing the MR

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR