std.encoding.sanitize should be usable in @safe

## forestix reported this on 2024-02-12T22:20:26Z

### Transfered from https://issues.dlang.org/show_bug.cgi?id=24391

### Description

````markdown
The offending line:

> return cast(immutable(E)[])array[0 .. offset];

ldc2 says:

Error: cast from `char[]` to `string` not allowed in safe code
````