chore(main): release launchdarkly_common_client 1.2.0

[LaunchDarklyReleaseBot]

:robot: I have created a release beep boop

1.2.0 (2024-03-18)

Features

• Update common-client to use common 1.2.0 (#144) (cd704ec)

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[LaunchDarklyReleaseBot]

:robot: Release is at https://github.com/launchdarkly/flutter-client-sdk/releases/tag/launchdarkly_common_client-v1.2.0 :sunflower: