Fastify v5 coordination

[mcollina]

Task lists:

• Create 4.x branch
• Land next into main
• Issue v5.0.0-alpha.1 release with the next tag on npm.
• remove all deprecations done in v4
• Update all official modules for the v5 release Update modules for v5 #5116, and issue releases for them with the next tag on npm.
• Write the upgrade guide.
• Write blog posts and coordination with OpenJS marketing
• Issue Fastify v5.0.0 as latest on npm.
• Retag all official plugins as latest

The target date is July 19th, but it can happen sooner or later.

[mcollina]

cc @jsumners @Eomm @gurgunday

[jsumners]

Going to try and tick off what I can when I'm able.

[mcollina]

I would try to get #5061 lined up too, but this is entirely optional.

[jsumners]

I/We need to do a pass or two on what we deprecated in v4 and remove what should be removed in v5.

[gurgunday]

And just FYI, a lot of the deprecated stuff is still in the codebase, they should be removed before the full release

[gurgunday]

These shorthand types are missing too, but I’ll look into them: #5444