ci: check version placeholder in release PR

[individual-it]

Description

Doing the check whether there are still version placeholders on the tag is too late. So I'm proposing to do this check in the release PR of ready-release-go.
That way the PR cannot be merged and a release created when there are still placeholders

Related Issue

• Part of dev docs list environment variabls as introduced in version 'next'. #1933

Motivation and Context

Block the release as long as there are still placeholders in the code

How Has This Been Tested?

wccs

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Technical debt
• Tests only (no source changes)

Checklist:

• Code changes
• Unit tests added
• Acceptance tests added
• Documentation added