Bug 18213: (follow-up) Correctly sort facets

Previously we sorted alphabetically - that works for 1-9.
With a 10th facet category we should sort numerically

Signed-off-by: Nicolas Legrand <nicolas.legrand@bulac.fr>
Signed-off-by: Alex Arnaud <alex.arnaud@biblibre.com>

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>

Koha/SearchEngine/Elasticsearch/Search.pm

@@ -509,7 +509,7 @@ sub _convert_facets {
         push @facets, $facet if exists $facet->{facets};
     }
 
-    @facets = sort { $a->{order} cmp $b->{order} } @facets;
+    @facets = sort { $a->{order} <=> $b->{order} } @facets;
     return \@facets;
 }