[Perl/perl5] 4ea83e: RMG: Remove Travis CI References

[Elvin Aslanov via perl5-changes]

  Branch: refs/heads/blead
  Home:   https://github.com/Perl/perl5
  Commit: 4ea83ef92cb66974a3fbfedbbc99ec79f85ad522
      
https://github.com/Perl/perl5/commit/4ea83ef92cb66974a3fbfedbbc99ec79f85ad522
  Author: Elvin Aslanov <rwp.prim...@gmail.com>
  Date:   2023-08-29 (Tue, 29 Aug 2023)

  Changed paths:
    M Porting/release_managers_guide.pod

  Log Message:
  -----------
  RMG: Remove Travis CI References

Since it's obsolete.

Replace with GitHub Actions where appropriate