writers: Allow string paths

Before this change, it was not possible to use string paths,
because then the `types.str.check` would succeed. So the only paths that
could be used were ones from the local filesystem via e.g.
`./some/path`.

We can easily fix this by using `types.path.check` instead to determine
whether we are dealing with a path.

This notably also allows using Nix-fetched sources as the content, e.g.
`fetchFromGitHub { ... } + "/some/file"`

0 files changed, 0 insertions, 0 deletions