feat: Assign code owners

From the docs
<https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/about-code-owners>:

> Code owners are automatically requested for review when someone opens a
> pull request that modifies code that they own.

.github/CODEOWNERS

@@ -0,0 +1 @@
+* @linz/li-topo-data-engineering