atftp: add patch to fix build error

atftp: add patch to fix build error

This patch fixes the following compilation build error for gcc14:

tftpd_pcre.c:109:37: error: passing argument 1 of 'pcre2_substring_list_free_8' from incompatible p
  109 |           pcre2_substring_list_free((const PCRE2_UCHAR **)substrlist);
      |                                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                                     |
      |                                     const PCRE2_UCHAR8 ** {aka const unsigned char **}
In file included from tftpd_pcre.h:24,
                 from tftpd_pcre.c:35:

I have also submitted the change to the upstream project:
https://github.com/madmartin/atftp/pull/2

Signed-off-by: Florian Eckert <[email protected]>