Revert last change using unformatted, but this time use the DT descriptor

Author: 14NGiestas

test/example/strings/example_padr.f90

@@ -1,13 +1,13 @@
 program example_padr
-  use stdlib_string_type, only: string_type, assignment(=), write (unformatted)
+  use stdlib_string_type, only: string_type, assignment(=), write (formatted)
   use stdlib_strings, only: padr
   implicit none
   type(string_type) :: string
 
   string = "right pad this string"
 ! string <-- "right pad this string"
 
-  print*, padr(string, 25, "$") ! "right pad this string$$$$"
+  print '(DT)', padr(string, 25, "$") ! "right pad this string$$$$"
 
   string = padr(string, 25)
 ! string <-- "right pad this string    "