Currently using php 7.2 to production (and everywhere), which has EOL at 26.11.2020. We can upgrade to php 7.3 (since we already test our code for that), which has EOL 26.11.2021. That gives us 1 year to test php 8 (see PLANET-5434)

Tasks

• Change php version to our base docker image
• Test to see any irregularities
• Push it to production
• Check plugins on different NROs if they work with the new version (dev sites, check sentry for errors)