GH warnings when running `get-releasenote` action

When you run the `aio-libs/get-releasenote@v1.4.5` action, Github adds this warning (repeated three times):

> Warning: The `set-output` command is deprecated and will be disabled soon. Please upgrade to using Environment Files. For more information see: https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/

As the linked blog page states, the deprecation has been postponed but I'm assuming it's not a stay of execution.

To fix the warning, replace printing with [appending to the `os.environ.get("GITHUB_OUTPUT")` filename](https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/workflow-commands-for-github-actions#setting-an-output-parameter), if it exists.