Trigger OS merge action in TTI repo

[halimi]

Summary

References: https://github.com/TheThingsIndustries/lorawan-stack/issues/4603

Changes

• Add a github workflow that triggers the 'merge-os-to-enterprise' action in the TTI repo

Testing

Steps

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Results

Regressions

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Notes for Reviewers

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Checklist

• Scope: The referenced issue is addressed, there are no unrelated changes.
• Compatibility: The changes are backwards compatible with existing API, storage, configuration and CLI, according to the compatibility commitments in README.md for the chosen target branch.
• Documentation: Relevant documentation is added or updated.
• Testing: The steps/process to test this feature are clearly explained including testing for regressions.
• Infrastructure: If infrastructural changes (e.g., new RPC, configuration) are needed, a separate issue is created in the infrastructural repositories.
• Changelog: Significant features, behavior changes, deprecations and fixes are added to CHANGELOG.md.
• Commits: Commit messages follow guidelines in CONTRIBUTING.md, there are no fixup commits left.