4.19.1

What's Changed

• docs(typescript): fix typo by @jon-codes in https://github.com/fastify/fastify/pull/4861
• docs(testing): add plugin testing guide by @Ekott2006 in https://github.com/fastify/fastify/pull/4849
• docs: fix platformatic-cloud anchor id by @sher in https://github.com/fastify/fastify/pull/4863
• fix: Type narrow fix issue from PR #4823 by @aadito123 in https://github.com/fastify/fastify/pull/4869

Full Changelog: https://github.com/fastify/fastify/compare/v4.19.0...v4.19.1