fix: entries incorrectly mapped

This was not being mapped correctly since the `Base` object looks for
data -> attributes when the API response does not include for
collections.

Change the attributes parsed to look at data->attributes and then only
attributes.

Add test case

lib/prizepicks/objects/base.rb

@@ -5,7 +5,11 @@ module PrizePicks
   class Base < OpenStruct
     def initialize(resp)
       @resp = resp
-      super to_obstruct(resp.dig('data', 'attributes'))
+      super to_obstruct(attributes)
+    end
+
+    def attributes
+      @resp.dig('data', 'attributes') || @resp['attributes']
     end
 
     def data

test/prizepicks/api/endpoints/test_entries.rb

@@ -23,7 +23,9 @@ def test_entries
                                stub: stub)
           resp = client.entries
           assert_equal PrizePicks::Collection, resp.class
-          assert_equal PrizePicks::Entry, resp.data.first.class
+          first_entry = resp.data.first
+          assert_equal PrizePicks::Entry, first_entry.class
+          assert_equal 2000, first_entry.amount_bet_cents
         end
       end
     end