[CI] first-timer-response workflow failing

[vitorvasc]

The first-timer-response.yml workflow (#8733) is failing, seemingly due to an issue with multiline comments.

You can see an example of the failure here: https://github.com/open-telemetry/opentelemetry.io/actions/runs/21146906030

It looks like the output command is unable to process the format correctly when it encounters multiple lines:

Invalid format 'i plan to add documentation-only recommendations to the python zero-code instrumentation docs explaining:'
Unable to process file command 'output' successfully.

All the recent failures are here: https://github.com/open-telemetry/opentelemetry.io/actions/workflows/first-timer-response.yml?query=is%3Afailure

/cc @chalin @pratik-mahalle

[pratik-mahalle]

The workflow fails when issue comments contain multiple lines. The $GITHUB_OUTPUT format requires using heredoc delimiters for multiline values. Opening a PR with the fix.