Update manifest_test for Ruby 3.4.1

Author: simon04

test/lib/docs/core/manifest_test.rb

@@ -64,7 +64,7 @@ class ManifestTest < Minitest::Spec
       it "includes the doc's meta representation" do
         json = manifest.as_json
         assert_equal 1, json.length
-        assert_equal "{\"name\"=>\"Test\", \"db_size\"=>776533, :attribution=>\"foo\", :alias=>nil}", json[0].to_s
+        assert_equal "{\"name\" => \"Test\", \"db_size\" => 776533, attribution: \"foo\", alias: nil}", json[0].to_s
       end
     end