chore(release): bump version to 1.2.0

[amrrbakry]

Release 1.2.0

Bump the gem version to 1.2.0 and move the Unreleased changelog entries into the 1.2.0 section.

Included in this release

Added

• New :open_telemetry target with a default puma metric prefix (feat: Open Telemetry target #30)
• New formatter: (:json, :passthrough) and transform: (:cloud_watch, :passthrough) options for the IO target (Expose new transforms and formatters design #25)

Changed

• A custom formatter: on the IO target now receives the transformed telemetry; pass transform: :passthrough for the old behavior (Expose new transforms and formatters design #25)

Dropped

• The Targets::IOTarget::JSONFormatter constant (Expose new transforms and formatters design #25)

Fixed

• Telemetry runner stops cleanly on puma shutdown; no more IOError: closed stream errors, and publish errors no longer make puma exit (Error logging telemetry causes Puma to exit #31, fix: stop telemetry runner on puma shutdown #45)
• socket_telemetry! warns and stays disabled on platforms without Socket::SOL_TCP/Socket::TCP_INFO (Warn when enabling socket_telemetry on unsupported platform #23)

Release steps after merge

1. Tag the merge commit: git tag v1.2.0 <merge-sha> && git push origin v1.2.0
2. The tag creation triggers the release job, which publishes the gem to rubygems
3. Create the GitHub release with these notes

Note: the earlier v1.2.0 tag pointed at a commit with version 1.1.6; the release job failed on the rubygems duplicate check and nothing was published. That tag should be deleted before tagging again: git push origin :refs/tags/v1.2.0