Delay initializing the s3 client until it's needed to silence warnings

Dependencies

• [2] UGA45FNC Add a plugin for backing up builds in s3

Change contents

• replacement in src/lib/Hydra/Plugin/S3Backup.pm at line 17
  [2.2000]→[2.2000:2087](∅→∅)
  − my $client = Net::Amazon::S3::Client->new( s3 => Net::Amazon::S3->new( retry => 1 ) );
  [2.2000]

  [2.2087]
  + my $client;
• edit in src/lib/Hydra/Plugin/S3Backup.pm at line 42
  [2.2797]

  [2.2797]
  + unless (defined $client) {

  + $client = Net::Amazon::S3::Client->new( s3 => Net::Amazon::S3->new( retry => 1 ) );

  + }