PHP upgrade to 8.3

[mariacha]

Right now the sites (other that India) are running on php 8.1. This ticket updates php to 8.3.

We already did this quickly on wri-india (which no longer runs on Pantheon) and didn't see any immediate issues.

Dev tasks

• Upgrade php to 8.3 in the pantheon.yml file, and in the circleci file.
• Run code compatibility checker for 8.3 on the wri_sites folder and any custom modules for Flagship.
• Fix any compatibility issues found.

To test

• Review https://develop-wriflagship.pantheonsite.io/admin/reports/status and verify that the php version is now 8.3
• Visual Regression tests and Module upgrade tests have already been run to verify compatibility.

[mariacha]

There's not much to actively QA here -- primarily it was just looking at logs and VR tests. I'm going to say this is ready to deploy.