Gutenberg: v18.3.x plugin upgrade

[gutenberg-plugin-upgrade-bot]

Previous upgrade: #89707
Release notes: v18.3.0

Install and activate

• Install and activate v18.3.0-rc.1 on edge (######-code)
• Install and activate v18.3.0 on edge (D148368-code)
• Activate v18.3.0 on production (D148369-code)
• Request v18.3.0 AT upgrade (######-p2)

Testing

• v18.3.0 Desktop viewport E2E
• v18.3.0 Mobile viewport E2E
• v18.3.0 WPCOM core (D148369-code)

Publish internal announcements

• Slack: #team-calypso
• Slack: #dotcom-happy-announce
• P2: wpcomhappy

Wrap-up

• Clean up unused releases
• Add log entry to the Gutenberg Upgrade Log (pcoGjb-g-p2)
• Open a new issue for the next upgrade, transfer remaining tasks, close this issue.

Blockers 🤷‍♀️

Other Issues 🐛

Issues transferred from previous release(s)

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cc @Automattic/gutenberg-upgrades

[gutenberg-plugin-upgrade-bot]

Automated update:
v18.3.0 is available at https://github.com/Automattic/gutenberg-dotcom-woa-releases/releases/tag/v18.3.0 for AT to pick up.

[olaseni]

Calsypso E2E tests needed to be updated because the post summary is no longer expansible.

Issue addressed in PR: #90736

[gutenberg-plugin-upgrade-bot]

Automated update:

• v18.3.0 activation on edge marked as complete.
• Release notes updated to v18.3.0
• Updated the diff used for v18.3.0 core tests

[gutenberg-plugin-upgrade-bot]

Automated update:

• v18.3.0 activation on production marked as complete.
• Release notes updated to v18.3.0