Add CODEOWNERS file to designate code owners

> About code owners [1]
>
> You can use a CODEOWNERS file to define individuals or teams
> that are responsible for code in a repository.

[1]: https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/about-code-owners

.github/CODEOWNERS

@@ -0,0 +1 @@
+* @fractalsoft/developers