Get rid of unnecessary dependency

.github/workflows/linux.yml

@@ -39,7 +39,6 @@ jobs:
             perl -v
             cpanm Expect ExtUtils::MakeMaker Test::Pod Test::Pod::Coverage || cat /home/runner/.cpanm/work/*/build.log
             perl -Mparent -e0 || cpanm parent
-            cpanm List::Util
             rm -rf /home/runner/.cpanm/work/*
             cpanm --installdeps . || cat /home/runner/.cpanm/work/*/build.log
             perl makefile-expect-driver.pl Linux::Debian Linux::Ubuntu Linux Unix OSFeatures::Systemd OSFeatures::POSIXShellRedirection HWCapabilities::Int64

Makefile.PL

@@ -76,7 +76,6 @@ WriteMakefile(
     PREREQ_PM    => {
         'File::Find::Rule' => 0.28,
         'File::Temp'       => 0.19,
-        'List::Util'       => 1.45,
         'Test::More'       => 0.88, # done_testing
         'Test::Warnings'   => 0,    # listed here as well as in TEST_REQUIRES in case we've got a Ye Olde Toolchaine
                                     # and not even the CONFIGURE_REQUIRES above is understood

lib/Devel/CheckOS.pm

@@ -7,7 +7,6 @@ use Exporter;
 # if we're loading this from Makefile.PL, FFR might not yet be installed
 eval 'use File::Find::Rule';
 use File::Spec;
-use List::Util qw(uniq);
 
 use vars qw(@ISA @EXPORT_OK %EXPORT_TAGS %OS_ALIASES);
 
@@ -217,7 +216,7 @@ my $re_AssertOS = qr/$case_flag ^AssertOS$/x;
 my $re_Alias    = qr/$case_flag ^Alias\b/x;
 
 sub list_platforms {
-    my @modules = uniq sort grep {
+    my @modules = sort keys %{ {map { $_ => 1 } grep {
         $_ !~ $re_Alias
     } map {
         my (undef, $dir_part, $file_part) = File::Spec->splitpath($_);
@@ -236,7 +235,7 @@ sub list_platforms {
         grep { -d }
         map { File::Spec->catdir($_, qw(Devel AssertOS)) }
         @INC
-    );
+    )}};
 
     return @modules;
 }