Fix Performance/ExcessiveAllocations to exclude each calls without a block

spec/ameba/rule/performance/excessive_allocations_spec.cr

@@ -6,6 +6,7 @@ module Ameba::Rule::Performance
   describe ExcessiveAllocations do
     it "passes if there is no potential performance improvements" do
       expect_no_issues subject, <<-CRYSTAL
+        "Alice".chars.each
         "Alice".chars.each(arg) { |c| puts c }
         "Alice".chars(arg).each { |c| puts c }
         "Alice\nBob".lines.each(arg) { |l| puts l }

src/ameba/rule/performance/excessive_allocations.cr

@@ -52,7 +52,7 @@ module Ameba::Rule::Performance
     end
 
     def test(source, node : Crystal::Call)
-      return unless node.name == "each" && node.args.empty?
+      return unless node.name == "each" && node.args.empty? && node.block
       return unless (obj = node.obj).is_a?(Crystal::Call)
       return unless obj.args.empty? && obj.block.nil?
       return unless method = call_names[obj.name]?