Fix failure in event001-eric256

Using `split('')` to get the individual elements of a number or string is
a Perl 5-like way of doing this.  Unfortunately, `split` matches the empty
string at the *ends* of the string as well, hence one gets 9 elements from a
7 digit string.  The solution is to use `comb`, which is the correct way to
do this in Perl 6.

categories/wsg/advanced-2008/event001-eric256.pl

@@ -130,7 +130,7 @@ (Bool :$verbose = False)
     my $phone_number = 7323464;
     my @test_words;
 
-    for $phone_number.split('') {
+    for $phone_number.comb {
         say $_, "->", %digits{$_}.join('-') if $verbose;
         if (@test_words.elems) {
             my @values = %digits{$_}.values;