[chore] Fix prepare-release.yml (#9675)

**Description:** 

Fixes
https://github.com/open-telemetry/opentelemetry-collector/actions/runs/8139621131/workflow

```
The workflow is not valid. .github/workflows/prepare-release.yml (Line: 54, Col: 9): 
Job 'prepare-release' depends on unknown job 'validate-version'.
```

#9409 introduced some errors because the workflow is not tested on PRs,
#9668 partly fixed them and I mistakenly believed Github would notify me
of further errors in the workflow, the same way it did with this one,
but it did not.

.github/workflows/prepare-release.yml

@@ -51,7 +51,7 @@ jobs:
  # Releasing opentelemetry-collector
  prepare-release:
  needs: 
- - validate-version
+ - validate-versions
  runs-on: ubuntu-latest
  steps:
  - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1