Look for perl experimental lines in snippets (exercism#58)

Author: m-dango

lib/languages/perl5.txt

@@ -4,6 +4,9 @@ use warnings
 use v5
 use 5
 use feature
+use experimental
+use builtin
+no warnings
 use Exporter
 our @EXPORT
 #

test/languages/perl5_test.rb

@@ -5,11 +5,19 @@ class PerlTest < Minitest::Test
       def test_all
         code = <<~CODE
           package HelloWorld;
+
           use v5.36;
           use 5.036;
+
           use strict;
           use warnings;
           use feature qw<say>;
+
+          use builtin qw<true>;
+          no warnings qw<experimental::builtin>;
+
+          use experimental qw<refaliasing>;
+
           use Exporter qw<import>;
           our @EXPORT_OK = qw<hello>;