Remove extra assignment operations

src/spectator/dsl/example_group_builder.cr

@@ -38,10 +38,9 @@ module Spectator::DSL
 
     def build(parent : ExampleGroup?, sample_values : Internals::SampleValues) : ExampleGroup
       ExampleGroup.new(@what, parent, build_hooks).tap do |group|
-        children = @children.map do |child|
+        group.children = @children.map do |child|
           child.build(group, sample_values).as(ExampleGroup::Child)
         end
-        group.children = children
       end
     end
 

src/spectator/dsl/structure_dsl.cr

@@ -47,11 +47,10 @@ module Spectator::DSL
         end
 
         _spectator_given_collection Collection%collection, %to_a, %collection
-        %to_a = Collection%collection.new.%to_a
 
         ::Spectator::DSL::Builder.start_given_group(
           {{collection.stringify}},
-          %to_a,
+          Collection%collection.new.%to_a,
           :%group
         )