`format: off` deletes marked source code if a trailing whitespace is present

the code should not be deleted in either case, but on 2.2.0 I get the following:

```
julia> format_text("""
       #! format: off
       1+1
       #! format: on

       """)
""

julia> format_text("""
       #! format: off
       1+1
       #! format: on
       """)
"#! format: off\n1+1\n#! format: on\n"
```