fix(backport): Workaround not to fail if no backport is needed

[jfagoagas]

Context

The backport action fails if the PR does not need a backport. The issue is known and reported in sorenlouv/backport-github-action#127

Description

Add a workaround to check first the labels included in the PR and if any starts with backport-to- the action will continue executing, if not it finishes.

Checklist

• Are there new checks included in this PR? No
  • If so, do we need to update permissions for the provider? Please review this carefully.
• Review if the code is being covered by tests.
• Review if code is being documented following this specification https://github.com/google/styleguide/blob/gh-pages/pyguide.md#38-comments-and-docstrings

License

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[pedrooot]

Thanks for this! 🔝