v4.0.0

What's Changed

• fix: improve versioning documentation and add showcase example by @Xavier-Redondo in #163
• fix(core): avoid duplicated exports by @rodrigo1991 in #161
• feat!: use fastify 5.x by @franher in #173
• Scope iif deprecation to TElseNever overload usage by @Copilot in #176
• chore: bump deps by @franher in #178
• chore(release): v4.0.0 by @franher in #179

Full Changelog: v3.1.0...v4.0.0