Fixes typo in reference to version label

[dmikusa]

Summary

This fixes a typo in the version label reference when setting labels on the generated PR. Without this the semver: label isn't set and has to be set manually.

Checklist

• I have viewed, signed, and submitted the Contributor License Agreement.
• I have linked issue(s) that this PR should close using keywords or the Github UI (See docs)
• I have added an integration test, if necessary.
• I have reviewed the styleguide for guidance on my code quality.
• I'm happy with the commit history on this PR (I have rebased/squashed as needed).