Fix CHANGELOG.md formatting for PR #3766 reference

[Copilot]

Summary

Fixed a formatting inconsistency in the CHANGELOG.md file where the PR reference for open-telemetry#3766 was placed on a separate line instead of following the established format pattern.

Changes

The entry for opentelemetry-exporter-credential-provider-gcp in the Unreleased section had its PR reference improperly formatted:

Before:

- `opentelemetry-exporter-credential-provider-gcp`: create this package which provides support for supplying your machine's Application Default Credentials (https://cloud.google.com/docs/authentication/application-default-credentials) to the OTLP Exporters created automatically by OpenTelemetry Python's auto instrumentation. These credentials authorize OTLP traces to be sent to `telemetry.googleapis.com`. 
[#3766](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3766).

After:

- `opentelemetry-exporter-credential-provider-gcp`: create this package which provides support for supplying your machine's Application Default Credentials (https://cloud.google.com/docs/authentication/application-default-credentials) to the OTLP Exporters created automatically by OpenTelemetry Python's auto instrumentation. These credentials authorize OTLP traces to be sent to `telemetry.googleapis.com`
  ([#3766](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3766)).

The PR reference is now properly formatted on a continuation line with correct indentation, matching the format used by all other changelog entries in the file.

Impact

This is a documentation-only change that improves consistency and readability of the CHANGELOG.md file. No functional code changes are included.

Original prompt

According to the commits ahead, change the CHANGELOG.md file

---

💬 Share your feedback on Copilot coding agent for the chance to win a $200 gift card! Click here to start the survey.

[UltimatePlutoC]

You do not need to make additional changes for other PRs. Just focus on the problem at hand. The only task is: Fix CHANGELOG.md for PR open-telemetry#3792,