[12.x] Fix path to Str in exception markdown

[apreiml]

Otherwise showing an exception will fail with an exception, if the facade could not be found.

This error might have been introduced in v12.25.0

[AhmedAlaa4611]

As @rodrigopedra said:

The \Illuminate\Support\Str is aliased to \Str by default. So it shouldn't be missing.

Unless you manually reset the aliases on a config file or on a service provider.

Please check if you are not resetting any aliases.

There could be a carried-over configuration from previous Laravel versions.

On prior Laravel versions, one could remove or add aliases on their ./config/app.php file.

I think we need to revert this one?

[rodrigopedra]

@AhmedAlaa4611

Please read my comment on the related issue on my guess about the rationale behind this PR:

I guess more people reset their aliases, and it is better to not rely on class aliases on such a sensitive view.

Especially when the framework cannot guess in advance if the alias is available.

#56709 (comment)

It is best to be on the safe side, so IMO this PR is fine.