remove gdb-fortran-frame-string.patch file
    
    Remove the 'gdb-fortran-frame-string.patch' patch from Fedora GDB.  I
    have pushed an upstream test that covers everything that this test
    covered, see upstream GDB commit:
    
      commit 1c01b23603766fbca4ed4dd12fdd710860e6038e
      Date:   Fri Nov 4 14:51:11 2022 +0000
    
          gdb/fortran/testsuite: print values and types of string variables
    
    As this is just a testsuite patch, I'm not going to backport this to
    Fedora GDB, but when we next rebase, we will pick up this test.