MT#61800 Switch code to «use v5.40»

This will make available several new language features.

Change-Id: I7f88a0e6ba9bdc12383498a7ff77a9b9d5dd8ef5

Build.PL

@@ -8,6 +8,7 @@ my $builder = Module::Build->new(
     dist_author       => 'Kirill Solomko <ksolomko@sipwise.com>',
     dist_version_from => 'lib/NGCP/API/Client.pm',
     requires          => {
+        'perl'              => '5.040',
         'Config::Tiny'      => 0,
         'IO::Socket::SSL'   => 0,
         'JSON::XS'          => 0,

bin/ngcp-api-admins

@@ -1,7 +1,6 @@
 #!/usr/bin/perl
 
-use strict;
-use warnings;
+use v5.40;
 
 use English;
 use Getopt::Long;

bin/ngcp-api-ping

@@ -1,7 +1,6 @@
 #!/usr/bin/perl
 
-use strict;
-use warnings;
+use v5.40;
 
 use English;
 use Getopt::Long;

bin/ngcp-create-customer

@@ -1,7 +1,6 @@
 #!/usr/bin/perl
 
-use strict;
-use warnings;
+use v5.40;
 
 use English;
 use Getopt::Long;

bin/ngcp-create-domain

@@ -1,7 +1,6 @@
 #!/usr/bin/perl
 
-use strict;
-use warnings;
+use v5.40;
 
 use English;
 use Getopt::Long;

bin/ngcp-create-soundset

@@ -1,7 +1,6 @@
 #!/usr/bin/perl
 
-use strict;
-use warnings;
+use v5.40;
 
 use English;
 use Getopt::Long;

bin/ngcp-create-subscriber

@@ -1,7 +1,6 @@
 #!/usr/bin/perl
 
-use strict;
-use warnings;
+use v5.40;
 
 use English;
 use Getopt::Long;

bin/ngcp-credit-warning

@@ -1,7 +1,6 @@
 #!/usr/bin/perl
 
-use strict;
-use warnings;
+use v5.40;
 
 use English;
 use Getopt::Long;

bin/ngcp-delete-domain

@@ -1,7 +1,6 @@
 #!/usr/bin/perl
 
-use strict;
-use warnings;
+use v5.40;
 
 use English;
 use Getopt::Long;

bin/ngcp-fraud-notifier

@@ -1,7 +1,6 @@
 #!/usr/bin/perl
 
-use strict;
-use warnings;
+use v5.40;
 
 use English;
 use Getopt::Long;

bin/ngcp-get-customer

@@ -1,7 +1,6 @@
 #!/usr/bin/perl
 
-use strict;
-use warnings;
+use v5.40;
 
 use English;
 use Getopt::Long;

bin/ngcp-get-soundset

@@ -1,7 +1,6 @@
 #!/usr/bin/perl
 
-use strict;
-use warnings;
+use v5.40;
 
 use English;
 use Getopt::Long;

bin/ngcp-terminate-customer

@@ -1,7 +1,6 @@
 #!/usr/bin/perl
 
-use strict;
-use warnings;
+use v5.40;
 
 use English;
 use Getopt::Long;

bin/ngcp-terminate-subscriber

@@ -1,7 +1,6 @@
 #!/usr/bin/perl
 
-use strict;
-use warnings;
+use v5.40;
 
 use English;
 use Getopt::Long;

lib/NGCP/API/Client.pm

@@ -1,8 +1,6 @@
 package NGCP::API::Client;
 
-use strict;
-use warnings;
-use feature qw(state);
+use v5.40;
 
 use Carp;
 use Config::Tiny;
@@ -202,8 +200,8 @@ sub set_verbose {
 
 package NGCP::API::Client::Result;
 
-use warnings;
-use strict;
+use v5.40;
+
 use parent qw(HTTP::Response);
 
 use JSON::XS;