pino 7.8.0

What's Changed

Add flush function to types by @kblcuk in https://github.com/pinojs/pino/pull/1329
New features must always target the master branch by @mcollina in https://github.com/pinojs/pino/pull/1334
Refactor the mixing logic by @mcollina in https://github.com/pinojs/pino/pull/1335
Add action to check PR target by @jsumners in https://github.com/pinojs/pino/pull/1337
add option mixinMergeStrategy (to v7) by @alexpts in https://github.com/pinojs/pino/pull/1336

@kblcuk made their first contribution in https://github.com/pinojs/pino/pull/1329

Full Changelog: https://github.com/pinojs/pino/compare/v7.7.0...v7.8.0