Use Clone backend for Hash::Merge, not Storable

Need to avoid Storable backend, since it can't deal with regexps:

    https://rt.perl.org/Public/Bug/Display.html?id=50608

This should fix the Docker builds.

Build.PL

@@ -61,6 +61,7 @@ my $build = Module::Build->new(
         'Carp'        => 0,
         'IO::File'    => 0,
         'Hash::Merge' => 0,
+        'Clone'       => 0,
     },
     script_files => [ 'bin/stow', 'bin/chkstow' ],
     all_from => 'lib/Stow.pm.in',

META.json

@@ -29,6 +29,7 @@
       "runtime" : {
          "requires" : {
             "Carp" : "0",
+            "Clone" : "0",
             "Hash::Merge" : "0",
             "IO::File" : "0",
             "perl" : "5.006"

META.yml

@@ -24,6 +24,7 @@ provides:
     version: v2.3.0
 requires:
   Carp: '0'
+  Clone: '0'
   Hash::Merge: '0'
   IO::File: '0'
   perl: '5.006'

bin/stow.in

@@ -462,6 +462,9 @@ use Getopt::Long qw(GetOptionsFromArray);
 use Stow;
 use Stow::Util qw(parent error);
 
+# Need to avoid Storable backend, since it can't deal with regexps:
+# https://rt.perl.org/Public/Bug/Display.html?id=50608
+use Clone::Choose qw(:Clone);
 use Hash::Merge qw(merge);
 
 my $ProgramName = $0;