[Perl/perl5] fe7859: .gitattributes: pin *.fnc files as plaintext

[Elvin Aslanov via perl5-changes]

  Branch: refs/heads/blead
  Home:   https://github.com/Perl/perl5
  Commit: fe7859256d3a8e646ec90c7313a105c8d273db32
      
https://github.com/Perl/perl5/commit/fe7859256d3a8e646ec90c7313a105c8d273db32
  Author: Elvin Aslanov <rwp.prim...@gmail.com>
  Date:   2023-02-08 (Wed, 08 Feb 2023)

  Changed paths:
    M .gitattributes

  Log Message:
  -----------
  .gitattributes: pin *.fnc files as plaintext

Otherwise *.fnc file are being displayed as PostgreSQL in GitHub Linguist stats
Of which there's 0.5 % in total repository-wise